Fact is - or facts are:
- Wittgenstein was not a Marxist;
- Wittgenstein was not an anarchist;
- Wittgenstein was not a socialist;
- Wittgenstein was not a leftist of any kind;
- Wittgenstein was not a working class fighter;
- Wittgenstein was not interested in politics at all;
- there is absolutely no sign that Wittgenstein even understood what capitalism is, or even noticed its existence, much less that he was in any way interested in fighting it;
- Wittgenstein was not even a gay rights activist.
So whatever his opinion was on the subject of "gay marriage" is irrelevant to us or our standing in that subject. He was against strikes, for instance - and we don't take that in account in order to inform our position on strikes.
Evidently, there is also the fact that the OP grossly misinterpretates his standing on how words work. But even if there wasn't such misinterpretation, the point still stands: we don't care about what Wittgenstein thought - except perhaps on the very limited field of philosophy of language, where his opinion might hold some weight. And even then, philosophy of language is scarcely useful to the end of fighting against the bourgeoisie, toppling capitalism, and building a classless society. Or even to the much more modest end of achieving equal rights, under capitalist domination, for people of all sexual orientations.