There does seem to be a weird fixation on that people may consume alcohol - in addition to general paranoia.
Your child is, as someone sortof alluded to, in more danger from the parents and coaches on YOUR team than strangers, as any child is far, far more likely to be abused by someone known to them than a stranger.
As well, yeah, the 'peg is the hot crime bed of Canada but... it's Canada. It's like being the meanest Mouseketeer. In addition to that crime has significantly fallen in Winnipeg, afaik, it's not exactly Detroit. Which isn't to say bad things don't happen but given how the explanations of what may happen range all over the place - boy-crazy girls in the same room may do something to attract boys who will then, I dunno, go nutso and rape a room full of girls? Random boys will go nuts, bust into the room and attack a room full of girls. Adults roaming the hotel will bust into a room... there may be drinking going on among coaches, thus... I dunno what. There may be drinking going on among parents, thus, I dunno what...
And the OP apparently won't feel safe unless there's an adult (which, again, known adult more dangerous than strange adult) sleeping in the same room with a bunch of teenaged girls to ... protect them from bands of maurauding boy sports teams on raping and pillaging rampages? Or people who had a couple of beers. It just reads a wee bit paranoid and irrational.
Agree that if it's the association rule change it likely happened for a good reason and if there are parents who can't deal with teenagers spending a night away from them, team sports may not be the way to go.