I am just not sure what the issue is. Maybe I am missing your point. Maybe you missed my earlier comment where I said "I understand that you were not asking why people promote, but from understanding why they would promote, you come to understand what promotion means. IMO." IMO, people try to convert others because they believe that what they have is what is necessary for salvation and others are lacking it. That is where I was speaking from. IMO, what I said and what you linked are saying the same thing. Perhaps to you they are not, but conversion is frequently linked to salvation. One who is unorthodox cannot say "If you don't join my church you cannot be saved".
Non-Nicene persons cannot post with the intention of converting people to their religion. A specific example is that they may not start a "Ask a Mormon/JW/Non-Trinitarian/Universalist/etc." thread.
I do not think that the only reason why someone promotes a theology or religion is because they think that others lack what is necessary for salvation.
People can promote conversion to a theology or religion because people think that it is true, because they think that it will improves one's life, increase membership numbers in their church, or other reasons. One can promote conversion to a theology merely to increase the numbers of those who adhere to a belief or religion, so that the belief or religion becomes accepted by more people. There could be many reasons.
There is a difference between saying that "promoting is seen, basically, as something someone requires for salvation. You cannot say your beliefs are necessary for salvation. You may believe it, you may try to show why you believe it, but you cannot say it. Nor can you use it to say someone who self-identifies as a Christian, isn't," and saying that "Promotion is defined as encouragement of the progress, growth, or acceptance of something."
I could offer an example to try to help you understand. Someone could say that their religion teaches that X is required for salvation. To me, this would not be promotion, but stating their beliefs. However, if the person said Dawn, I urge you to do X so that you can be saved, that would be promotion. The first is a statement of beliefs, while the second involves encouragement.
Here is another example that does not directly involve the idea of salvation. Someone may ask, "does X group teach Y?" Someone could merely state what they teach, or they could say "come to our church next Sunday and find out for yourself!" Or, "why don't you meet with the missionaries to discuss this?" I would consider the second to be promotion. It is encouragement of acceptance of something.
My concern is that people will state their beliefs and inadvertently violate the no promotion rule (as you have defined it) by saying what they believe is required for salvation. There is also a very distinct possibility that they will be set up by others to violate the rules.
Defining promotion as saying that something is necessary for salvation also seems to negate these views that were once expressed:
[3] Posts or threads intended to inform about non-Nicene beliefs is not to be understood as promotion.
[4] Offering a non-Nicene belief as a statement of fact is not to be understood as promotion.
It is possible to merely inform of beliefs without promoting that belief. Even beliefs concerning salvation.