She sounds immature and certainly needs to know when to shut it. I do think you should let the director know what was going on even if you don't come back.

Playing devil's advocate here. You say your son had ignored her many times when she greeted him. This will tend to annoy adults, who will see this as a sign of disrespect. Shy kids and kids with ASD struggle with this and are often misinterpreted as rude, oppositional and passive aggressive. He may still be still be too little to understand, but eventually he needs to know how shutting down will impact how others see him. ESPECIALLY adults with chips on their shoulders.