where stand-up kinda gets unfairly viewed is that people look at the person doing the jokes and say "that's sarah silverman" instead of seeing it as a performance/persona that sarah silverman is doing
which is something that comics spend a long time trying to create and calibrate
some comic personas are closer to the actual person than others
but you're looking at a person who is telling jokes and doing bits to be funny/ironic/whatever
not a person who is giving you a speech or telling you the truth about what they feel
so from that perspective, i don't think you can ever "call out" a comic for being racist/sexist/homophobic solely based on something they say in a bit
because you still don't know anything about them, you just know the bit