The confusion may be cleared up by a brief history lesson.
Michael is part of (or seeking to become part of, I'm not sure) a hyper-traditional group of churches which call themselves the "true Orthodox." They are a small schismatic group, not in communion with the 5 ecumenically recognized patriarchs - Constantinople, Alexandria, Jerusalem, Antioch, and Moscow. They list a variety of reasons for this schism, but two things seem to come up a lot:
1) "Ecumenism" - this term is used a lot of different ways, and that's part of the confusion. The form of ecumenism that both sides consider wrong is the one that seeks a "lowest common denominator" between churches and then claims that they are one or that only that denominator is really doctrine. This is common among some of the evangelical churches - it is, in fact, the only unifying doctrine of the non-denominational churches (along with adament sola-scriptura and sola-fide, though theoretically one could disagree with those and be non-denominational; one could NOT disagree with "mere christianity" ecumenism and be non denominational). Because this allows for so much doctrinal wiggle room, it is called the "pan-Heresy" - it can encompas any number of "heresies" underneath it (technically something isn't a heresy unless an Orthodox Christian commits it and is anathematized - hence the quotes).
Because the Orthodox churches (in particular the Patriarch of Constantinople) are involved in things like the "World Council of Churches" and in dialogues with the Pope in Rome they are accused by the "true orthodox" as being in this same camp. We, however, see a big difference between whitewashing differences in an attempt to appear unified (ecumenism), and an honest dialogue in an attempt to bring the heterodox back to the Truth. If we didn't have that dialogue, we would be ignoring the Great Commission. If we fall into ecumenism in it's white-washing form, we ignore the commission of St. Jude to "contend earnestly for the faith once traditioned to all the saints."
Within this dialogue there is the possibility that compromises over smaller traditions can be made - things we don't consider central doctrines (things that can be changed). This is another place that disagreements arise, which leads us to the second hot-button issue.
2) Old Calander vs New Calander: This issue gives these groups the title "Old Calanderists" - perhaps a more common title (at least within the states). I'm not certain when the change took place, but at some point, in an effort to make our calander match up with actual astrological phenomena (to make it an accurate calander), the mainline Orthodox Church - the 5 Patriarchates - decided to start using the Gergorian rather than Julian calander. The Julian calander, while the traditional one of the East, didn't account for the leap year and so was continually off base. The Gregorian calander was created by the West long after the schism, so the East didn't have it, but it did accurately reflect astrology by accounting for a leap year every 4 years to automatically correct itself.
The accusation is that by using the Western calander from a post-schism West, we are committing ecumenism in its white washing form. So the Old Calanderists decry the practice and call us heretics for it. Note: there ARE communities who are in communion with the 5 patriarchs whoe use the Old Calander - the Julian calander. The Orthodox Church does not forbid its use, we just also allow a church / parish / monastery to use the Gregorian calander if they would like to, and encourage it. It is the schismatics who have dogmatized this issue.
And that's really why I disagree with them - they dogmatize legalistic issues and are hyper legalists, refusing to allow that customs and "little t" traditions change. They condemn us for allowing women (if they are contentious about it) to not wear head coverings, for allowing men and women to stand on the same side of the church, for allowing women to wear pants, for giving women communion while on their periods, for using an astrologically correct calander, and for talking to non-Orthodox.
Hope that helps!
Macarius