I can't imagine ever needing surgery on the piriformis-- it is deep, and therefore well protected. Since it doesn't act alone, even serious weight training is unlikely to cause it to grow enough to cause a compression problem. But, yeah, ain't no part of the body that isn't vulnerable to all kinds of things. However, surgery and/or drugs should be the last resort.

There's plenty of youtube and other video online that demonstrates piriformis trigger point release. That's fine: it isn't rocket science, it's just a few moments of ischemic pressure. But you shouldn't allow anyone to apply deep pressure directly to the center of the muscle, which might (rarely, but possibly) cause even more compression on the sciatic nerve that is either directly beneath the muscle or running thru the heart of the muscle. But the TrPs in the piriformis will usually be found very close to the sacrum and a few centimeters off its insertion on the greater trochanter of the femur--no danger of putting pressure on the nerve.

Five lateral rotators in the butt can be causing/contributing to the problem. In fact, the entire length of the nerve is vulnerable to impingement by covering muscle...in the buttocks, in the posterior thigh.