This absurdity of pretending that men who call themselves women are actually women should certainly be open to mockery, as it's so ridiculous - both in itself, and the fact that so many people are entertaining this misogynistic delusion.
If there is an absurdity, it is in this type of framing. Imagine, men entering women spaces! Don't they know their place? Wait..
Yes, it's the sex that has such a high proportion of predatory, dangerous and creepy individuals that the other sex need segregated spaces for their own safety and dignity. Which is also the sex of most of those who are actively trying - and often succeeding - to undermine and eradicate these safe spaces under the guise of so-called "trans rights".
The end goal of these men is that they be permitted, by law and policy, to disregard women's consent and boundaries with impunity. Not only is this wholly unacceptable, but the arguments they are using in pursuit of this goal are ridiculous. So of course comedians are going to ridicule this. I'm glad they're doing so; this misogynist activism needs all the mockery it can get, it's part of the path towards undoing the damage already caused.
What is this thing about some groups being "off limits" while others are fetishized and babied?
There's no longer anything "brave" in making a joke about a "safe group" to joke about.
In today's day and age since trans is the new sacred cow amongst certain crowds in the Western world, it seems natural that that would be the subject of jokes.