I don't have time to reply at length now, but on the idea that incense provides "comfort," while I acknowledge the particular point when talking about the presence of the bodies of the deceased, I would note that incense in many contexts has become deeply problematic and anything but a comfort, due to allergies and sensitivities.
One of the most unpastoral choices I have ever seen made in a liturgy, was the insistence on the use of incense at a funeral, which saw one mourner standing outside the church door, because to come in would have meant a trip in an ambulance.
So my view is that if a funeral happened, and incense was used despite the knowledge someone intending to attend had an allergy to incense, and the solution was to shove them in the external door, that would be absolutely unacceptable.
For my part, all funerals I did were in the UCC, and most were memorial services as there had been cremations, with the cremated loved one interred separately or taken home by the bereaved, and all that were not involved the urn with the cremated remains being present, or the embalming of the loved one, and no incense was used.
A funeral has not yet happened in my new ministry, but it will, since I have some elderly laity, including two who suffered severe heart attacks, and some with a history of serious cancer, in remission thankfully, and one with a neuro-degenerative disease and my policy as I have said before is to do what the mourners desire, but I have preached against cremation in church and I have encouraged members, publicly and privately, to arrange for burial, and as many of my people are impoverished, I have connected them with resources, for example, Clark County buries in coffins anyone who cannot afford the services of a funeral home, as well as unclaimed bodies, and coordination with the Department of Public Health does allow for the use of that resource while still providing full funeral and graveside services, and equivalent resources exist in the other counties where members of my two congregations reside, and other members of more resources have made advanced arrangements involving inexpensive coffins.
Within Orthodox communities, I have never heard of anyone having an allergy to the incense they use, and it is used in
almost all of their services. However, the Trisagion Prayers, which lack incense, usually, are an integral part of the Orthodox funeral services, as is the Burial, so anyone who was not Orthodox, had an allergy to Orthodox incense, and wished to attend, could go to those in complete safety. I have never heard of this being a problem, however,
There are different kinds of incense, and some kinds of incense used by Anglicans are made differently than what the Orthodox use, and I am allergic to it. For example, self-igniting incense, especially the many varieties of self-igniting incense used in Joss Sticks, in Chinese, Japanese, Korean and Vietnamese religious rites (syncretically, in Buddhism and Shinto in Japan, and in Buddhism, Taoism, and the traditional Chinese folk religion, including Confucian observances, in China, Korea and Viet Nam, as well as minority indigenous religions, I am moderately allergic to, in that I get an instant headache.
However, as far as an allergic reaction requiring hospitalization, with Anaphylactic Shock, where one might need to carry an Epi-pen; kyrie eleison; I have never heard of that in the Orthodox church, but I have heard of it in the case of Joss Sticks, and exposure to marijuana fumes once caused me to experience that.
I suspect incense allergies in Western churches are mainly to additives or the combustion material, rather than the core ingredient, which in the Orthodox church, is the resin from certain trees. There are also special varieties of charcoal used.
I follow problems in the Orthodox communion very carefully, so if this is a major issue, I would be surprised I hadn’t heard of it, but I do not claim omniscience, so this could ne a thing, and it might also be unknown to me because discussions of it are in modern Greek, Russian or other languages unknown to me. For example, I am aware of such shocking scandals as the drowning of a baby during baptism by an incompetent hieromonk in Moldavia, who was convicted of negligent homicide, but before his prosecution even began, he was immediately deposed (because killing anyone, even accidentally, is a disqualifier for Orthodox Holy Orders, so if an Orthodox priest were to kill someone while drunk driving, that would be the end of their career, and a disqualifier from becoming a priest).
On that basis, if Orthodox incense ever killed someone, it could disqualify all the clergy at the service, so based on that, if someone has a real allergy to sandalwood resin, which is one of the most common types of resin used in the manufacture of different varieties of incense, they need merely to communicate that to the clergy. Most Orthodox incense is made in monasteries and convents, along with the fuel used in the thuribles.
However, I have never seen an Orthodox church that is not filled with clouds of incense after a liturgy, even with the windows open, or heard of someone with a serious allergy to it, but if it did occur, provisions could be made.
It is also possible, and worth considering, that the prayers of blessing that accompany the use of incense do protect the laity, including people like me who are allergic to tobacco smoke and smoke from campfires, indeed, almost all smoke makes me sick, except liturgical incense of the type I have encountered in Orthodox churches and most Catholic and Anglican churches that use it, from adverse effects. This is not a fringe opinion; I know a retired OCA bishop and a ROCOR auxiliary bishop who hold this and certain related opinions, but on discussing the issue with them, both were also prepared to accommodate people who had a known allergy in a number of ways, if that ever happened, which they had never heard of.
So, the bottom line is what happened in the funeral you saw was an avoidable tragedy, as I can think of about ten different ways of preventing it, including some that would have allowed for the use of incense, and separately, I have never heard of anyone getting sick from the incense in Orthodox churches, but it is obviously possible, if exceedingly uncommon, and anyone with a known allergy should contact the parish they will be visiting for any reason and accommodations can be made.
If you yourself have a serious allergy to incense, you should contact the Assyrian church in Sydney if you ever find the opportunity to visit it, as Assyrian parishes frequently use plain sandalwood resin incense from a small stationary thurible, which the laity will with their hands conduct the fumes up to their face before partaking of the Eucharist, but this is not always done, and some Assyrian parishes don’t do it at all, for instance, I have never seen it at St. Mary’s Assyrian Church of the East in Detroit. I have no doubt accommodations would be made.