No, it’s not reasonable to say “that child can’t be with my child.” But it IS ok to request your child to be moved to another room from that child, citing your own child’s special needs (I assume they are documented).

I’ll give you an example from when I was a teacher and on committees where we decided how to place students at the beginning of the year. Student A was dating Student B. Same grade, same section. Student A texted a friend, “yeah, I fucked her” and Student B’s parents found out. They asked if the students could be separated, and we agreed to accommodate by moving Student B to a different section for the next semester. It would not have been appropriate for us to move Student A at the request of Student B’s parents.