From what I’ve read, it puts a burden on teachers.

Children are curious and they aren’t stupid. Any honest question that may result in even the slightest shading of talk of “gay” could have serious repercussions for them.

This is not a subject that teachers willingly discuss with very young children; they would much rather it be discussed at home. But if it isn’t, and little Emma talks about her aunts that are married to each other, it could cause a discussion. Emma can be happy as a clam, and her family accepting and understanding, but the very topic is now forbidden. On any level.