I echo what the others have said, it's a screaming red flag to me also. These are 10 year olds not 15 year olds, even so, such a policy is still a red flag to me.
Just the mere fact that you are posting about this, to me, signals that your instinct is on high alert and that you should not rationalize away this instinct. You should heed it and respect it, it is there to protect your child.
I read the book, Protecting the Gift by Gavin De Becker,
and the one thing I took away from it, and my husband also, was to honor maternal instinct. Women are gifted with this instinct to protect their children. The problem is that we no longer listen to it, the more evolved we become as humans the less we listen to our instinct, we try to rationalize it away, unlike a wild animal would. Women are also expected to be 'nice and 'polite'. One example he gives, is a women and a child alone in an elevator. A man awaiting the elevator stands before the open doors, women and child inside the elevator. The women immediately senses discomfort, and her first instinct is to get out and wait for another elevator, yet as not to make the man feel badly, she stays on. So there. She has placed a strange man's feelings above her instinct to protect her child. Now she is enclosed in a metal box with a stranger that has raised her hackles and she has ignored that slight twinge of discomfort that was her maternal instinct talking. And the author states that it can be subtle or a loud abrupt alert, either way, there is that uncomfortable feeling that just will not go away......that is your instinct speaking to you.
The author, who seems well qualified to write this book, tells story after story of women who had brushed off, or rationalized, or ignored warning signs before an event that harmed their child took place. Then in hindsight, each had realized that they had received plenty of signs, prior to the event, therefore that something was not right, yet they brushed off those instinctive feelings. It is just an example of how a modern women ignores that slight twinge, actually her strong primal instinct. Whereas an animal would have bolted without giving it a second thought, and responded to her instinct immediately.
The main point the author makes is that a predator is only able to commit the crime if he can get the victim alone, he must do that in order to gain control so that he may commit the crime. Therefore the author gives examples of time after time, when a predator separates the child from the parent, the group or from a crowded place and then, only then, gains control and can commit the crime.
Really, the book was an eye opener to me. My husband read it too, then said he would buy copies for his sisters (both mothers also).
Well, if you got through my long drawn out response, thank you. I would urge you to listen to your instinct, it is there to protect your child. After all if you ever had an organization for children, would you deliberately make a point of separating, or downright banning the parent from the event, knowing you were taking a child away from home? Of course not.
ETA- Oh my gosh, I just noted your final post, so glad that you have found another choir!