David, I'd like to point out a few issues in your post.

First, I don't see any moral equivalence between pornography and homosexuality. The first is a perverse form of entertainment, the second is a way in which people love each other.  Homosexuality is only "immoral" because religions say it is; pornography doesn't need any underlying religious doctrine to be declared immoral, it is inherently so.

You write, "For the Yeshiva (and for all fair-minded Jews who are instructed to not
judge people, only actions), the actions of an alum are separate from
the legitimacy of the person himself." If we are only to judge others by their actions, then how can you argue that the Yeshiva can judge its homosexual alumni and their parters as unfit to be together at the reunion?  Did the Yeshiva observe their actions? Did they watch them violating the commandment against homosexual sex?  If not, then by what actions can they be judged?  As far as I know, there is no commandment against being homosexual, only against two men having sex with each other.

Believe me, I understand the issue and I understand why the Yeshiva is doing what it's doing (even if I disagree with it). But by your own standards, David, these gay alumni should be allowed to attend, as long as they don't have sex on the premises.