That's not really generalized, since it's specific to abortion and murder. A generalized emergency taboo button would be a custom where it's considered polite to ask people to taboo a word (if you think this might help the discussion), and impolite to ignore this request.

My intent wasn't to contextualize, thanks for making it more explicit.

(...) and it's hard to give a compelling justification for it in a quick sound-bite that you can drop into an in-person discussion.

Don't Try This At Home Capsule: Some dark arts work really well. I've found that out firsthand, both accidentally/involuntarily and in a tiny-sample controlled test (not scientifically relevant, but anecdotally sufficient for me to have good intuitive confidence thanks for confirmation bias vs VoI and different in expected utility). This was before I learned of confirmation bias and the risks of Dark Arts, though.