Risk of developmental difficulties increases with mother’s age.
Father’s age too, but I think that’s a lesser impact.
Also, having a threat towards women (but not men!) is just part of the selling point.
I’m not at all saying that these are good arguments, but they might be the motivating factor. Personally, I think it’s mostly about the threat to women.
“I don’t know enough to have an informed opinion about this” is an admirable stance to take.
When it’s a cop-out for not wanting to be politically informed, it’s a crappy place to be. It can sound a lot like “I don’t know and I don’t care”.