I can't even begin to understand how someone could think they could talk to a young child that way. He has a diagnosed anxiety disorder with a PTSD pattern in his brain scans. He is working seriously hard to overcome profoundly difficult physical and emotional struggles... but no little boy, next time SMILE or you will have your learning options limited even further.
Where do you start with a teacher like this?
Happily, does he have an IEP, and if so is there a behavior plan?
Such a plan spells out explicitly what must be done to proactively prevent problems (like anxiety) as well as what consequences can be used when there are problems. It sets real, enforceable limits on school staff.
Seems to me it would be a place to start.
DeeDee
ETA: now I see that you're working on a 504. I would try to hold out for an IEP, with explicit instructions on discipline strategies...