This is the legal advice sub so I’m going to be a bit circumspect. That said, we’re talking about fourth graders here. They say the darndest things. Please don’t take this as an indictment of your daughter or LGBT people in general (I’m a gay man ,FWIW).

It’s entirely inappropriate for the school to threaten your daughter with any sort of sanction for being who she is. Full stop. If that is what they are doing, and I’m not clear from your post that is what is happening, hit them so hard with the law that they land in the century they think they’re in.

That said, if they’re actually saying your daughter needs to cool it, in the same way that they’d ask Timmy to stop talking about Sally or the cheerleading squad, then have a conversation with your daughter about appropriate conversations.

Finally, if all of this is because some other fourth grader heard the words “gay” or “lesbian” and that makes their redneck parents uncomfortable, stand your ground and lawyer up.

Good luck.