Well if you look at SEKs post it sounds to me like the boys are welcomed but dad needs to stay in the hall. Maybe I'm reading too much into it but that's the impression I got. I don't know why you wouldn't want his experience in the room but every club is allowed to make that choice!
Obviously some bad blood between the adults involved and some pay back for leaving that particular club. However, the focus should have been the kids and nothing should have been said in front of Mason or his friends. The coach should have pulled Mr. Turner to the side and discussed it in private and let him complete the practice session. You have the right to move to any club that you feel best develops your child's skills. However, don't be surprised when the club you left isn't that accepting of you returning for a practice.
I'd love for Mason to come to our club and practice with my son. Turning away a National and State Champ just hurts the other wrestlers that would benefit from practicing with such an accomplished wrestler.