First of all, I'm sorry to hear that, and I sympathize with your plight!
I definitely think there are some jokes that can be cut for community standards. What is acceptable in Kansas might not be the same as what's acceptable in Portland. (That said, my 10 year old son is currently in a production of TBGS here in Texas and I'm not concerned!) So I think you did the right thing to contact the parents to prevent rumors from spreading in your community. (When I first did this show, I had 5 parents hold out their kids and didn't tell me until the day of the performance! It's best to nip these things in the bud.)
This is a play that on occasion riles people up. It's also a show that's been produced 2,600 times and has appeared in 45 different countries - I'm guessing that a few of those have cut jokes here and there, and some others have been the unexpurgated version.
As a parent, I understand the idea of protecting your children. But I think some parents need to relax - especially in high school. If you were doing Shakespeare, there would be far worse in the script, but the parents wouldn't complain.
In any event, I think you've done the right thing.