I imagine their thought process is if the parents are supportive the child or school will tell them about the pronouns and the child will get called the "right" thing everywhere.

If not, the child at least will get called the "right" thing at school instead of the parents insisting on biological sane science-based pronouns or pulling them out.

It's actually a greater indictment of them that they are capable of thinking rationally about this as it shows when it comes to gender swaps they just choose not to be rational.