OK, courageous GUEST:

If Linda goes to a concert (is she attending or singing?)...

If she's attending, she has 3 choices: stay and say something, stay and say nothing or leave. I suspect she does not toss her can of Diet Pepsi at either the offending individual or the stage.    If she's singing the concert, she has no choice--she stays.

By the way, how did she find out the person is a Republican or a fundamentalist Christian?
Is the person yelling at her that she has no right to sing "Will There Be Any Freight Trains In Heaven?" since she's not "born again"?   I'd say she has a right to feel uncomfortable.

Pretty clearly wretched sensationalist journalism, as Don says. But that won't stop giant intellects like yours from reading the worst possible interpretation into it