Somewhat ironically you must have an _approved_ cause, or you may be judged as much as not having one. To be fair I've found this is far more prevalent in SF than the South Bay, so I think that's where it comes from.
I find it a hilarious instance of California insularity that the grandparent post thinks it "doesn't matter what it is" -- I'm guessing that he'd failed to consider the fact that non-left causes even exist.
In this case, you would be guessing wrong. My omission is not evidence of insularity but of walking on eggshells. I've made this point to many up here and found they are more willing to discuss and agree if I omit the narrow scope of "any cause".