Actually, if the figures quoted are right, and rugby has 4 times the concussion rate of ice hockey and 8 times that of gridiron when played by children, they're very probably right.
This isn't about adult players making the choice to play the sport in a particular way, but schools rugby and teachers telling kids they have to do it 'this' way whether they want to or not. If parents aren't happy with the way a sports club's run, they can pull their kid out of the club and voice their concerns to the governing body (or even the police). Much harder to do that with a school.
And there are lots and lots of ways of combatting a 'sedentary lifestyle' habit and juvenile obesity without risking concussion, broken bones, and neck injuries. And it's not about statistics - it being 'only' 4 or 5 in 1,000 - if my kid's one of the 4 or 5 I want the law to give me a way of (a) finding out what happened, and (b) nailing the stupid sod who let it happen.