The point in both cases here is to make a criticism, so the pertinent question is really whether the criticism is valid. It's possible to make a valid and important criticism while being factually incorrect.If whether or not it actually happened is irrelevant to if it's fact if enough people are talking about it, then it just comes down to arguing what the bar for "enough people" is.
The reason it doesn't really matter whether there is a specific 10 year old out there who was or was not denied an abortion is that that the law being criticized would, in fact, make it extremely difficult for such a child to get an abortion. There are going to be countless people, including children, who suffer because of a lack of access to abortion services due to that piece of legislation.
Pointing to a single highly-publicized but false instance of a child being denied an abortion and then claiming that this evidenced the law in question was harmless or that children were not being denied abortions would be just as false. The criticism is valid whether or not the facts are correct.
The people actually passing or celebrating abortion bans don't actually care about this shit. They believe it's a good thing if a sexually abused child is denied an abortion. What they don't like is people being encouraged to sympathize with someone who might need an abortion, because it's easier to sell their beliefs to people who aren't as fanatical as they are if those people can be persuaded to view those seeking abortions as bad and selfish and promiscuous. The story must be dismissed as false not because it would be bad if it were true, but because it might look bad if it were true.
This "64 genders" thing doesn't actually have a factual component. It doesn't even represent anyone's real beliefs. Most people with a decent amount of education in this topic could probably argue that there are an arbitrary number of genders, but that argument has little purpose outside of an rhetorical exercise and, if you're capable of making it, you're already capable of understanding why the number isn't 64 (or indeed, any specific number). The "[insert number] genders" talking point isn't actually from any kind of academic or "social justice" discourse, it's just a bad right-wing meme from the tumblr era which, at this point, is just a boomer joke, and the most inexplicable thing about this case is how few people seem to have clocked that it's a boomer joke.
By the way, this school was also clearly teaching children to identify as attack helicopters. Is that true? I guess it doesn't really matter. But I bet when these kids went to the school library they were trying to swipe right on the books. Seriously if you want to be a dude with no balls you should try getting married. Why aren't M&Ms sexually attractive to me any more?