OP,
You will come across this everywhere I think.
I certainly think it is possible to encourage friendships with people you prefer.
When your children make friends, you definitely are subject to their friends parents, parenting style.
You can influence and encourage other friendships.
I am absolutely with @Testina in having open and frank dialogue.
My boys learnt about the deathgrip from me, as a doctor friend mentioned that her and her colleagues were noticing a growing issue of porn addiction in young males in their 20's and 30's.
The choking bullshit is definitely something that young teens need to be aware of.
I always told my children to ask ANY questions of ME and not their friends, from a very young age.
I told them I would give them any information they wanted and that it was better to get facts rather than fiction.
I can absolutely understand your distaste, but knowledge is power and I think it is very important children get the information they need from a safe source.
If these parents are very relaxed and hands off, they may well be the same about alcohol too.
Encourage other friendships if you can, but moving school for this reason alone is not the answer, it would possibly make her more vulnerable.
Being the new kid at 10, in the class, is no laugh.