Hellenic riot i think you need to define what you mean by abusive and degrading. (I put my definition at the end of the post) at no point does the thread in question violate any of the two words. A topic about it is fine to have as a discussion on the issue does not degrade or abuse a group of people. You say it clearly violates the terms but the closest i see from reading the forum of any sort of degrading comes from calls that the left are at fault. This has no direct link to transgender. The site has the right to lock people from speaking but it seems that you are attempting to block the discussion from occuring at all. If there are transgender people on the site and they cannot handle people who think their lifestyle choice is wrong then why should we be barred from talking about. If that is the logic then all forums should be banned as every topic might offend other members.
If you are going to lock i, quote the part that you believe is the abusive or degrading. From where i am sitting i see an abuse of power by the mods and you need to clarify as to why this decision matches the rules set by the page.

Degrade: to treat (someone or thing) poorly and without respect.
Abuse: the use of harsh ans insulting language