As I was reading it, before you got to the part about involving outside law enforcement, that's where I landed. I have a kid who is a foot taller than all the kids, too, that doesn't mean that he's not in danger from someone pulling a knife or god forbid bringing a gun to school. I don't know that this helps, but you're not an over zealouus mom, just concerned for your child's safety. 

 Thank you. That’s exactly how my husband and I are feeling. We aren’t even asking them to expel the kid, but we do want them to take the threats seriously and don’t understand why his small size or on the spectrum diagnosis matters. 

 It's so frustrating. I hope it gets resolved quickly!