Terribly rude owner

We were asked to attend a music worksop with our children. When we arrived, there was another family waiting to be assisted at the classroom door, so we stood in line behind them, waiting to be assisted as well. The family in front of us were immediately assisted, but no-one came to assist us. The door was at the front of the classroom, so me and my son were in full view of everyone. After we waited for about 15 minutes, the owner abruptly walked over to me and said (while pointing his arm away from his body): "Ma'm, I'm gonna have to ask you to go stand somewhere else. Everyone is looking at you." I was so dumbfounded and shocked that I couldn't think to say anything in response. This appeared to agitate him even more, so he bent down (he is taller than me) and exclaimed: "Are you in or out?!" (as if he was admonishing some naughty child). He felt confident enough to do this in full view of the entire classroom full of people. Asking people to attend an event and then treating them like stray dogs by chasing them away is just unfathomable to me. I cannot remember the last time anyone was so rude to me (if ever!). I'll find another school for my son to learn to play piano at. If he is this rude to parents, how does he treat the children? Disgusting!