I have no issue with men wearing dresses or make up, if that's what they want. The bit I disagree with is when they claim that they're actually really female.
That's where the comedy comes from in Monty Python - it's clearly a man, and he's pretending to be a woman, and that's funny.
A man dressing in clothes that society might be predisposed to consider feminine, is not funny, and should not be mocked.
No more than a woman wearing trousers with short hair should be mocked.
But a man saying he is a lady, is wrong, and therefore I will dispute that assertion, and I might also laugh, though that's probably unkind and uncalled for.
It depends on the circumstances.
These particular circumstances are pretty silly.