I work with a company on a regular basis who's content in past years has included rape, drug use, sex, murder, lynching, torture, racism, genocide, and Nazis just to name a few.
The company as a whole has always known the content could drive patrons (not just older) from the theater because we work in small spaces and seeing some of those things happen 10 feet in front of you can be disturbing, but we owe it to the work to not shy away from it. Like Rebbe said, their reaction is to the content, not necessarily the presentation.
The other tactic I've seen used by a cast is to "perform for themselves." Go into the performance knowing the audience won't get it, and it's perfectly ok. Just enjoy being onstage with each other and truly live in the moment and everything else be damned. This is something I had to do as an actor in a run of "The Good Woman of Setzuan" I performed in college. We started off being upset that people were leaving but by the time we closed we were having so much fun onstage we could honestly have performed to an empty house and been so happy to just share the space with each other.