I've been trying very hard most of my life not to have mental or discussion taboos. I may find a position, request, action, etc disagreeable or even reprehensible, but I see no winning outcome in making it a taboo. And I struggle to visualize a debate itself that is morally unacceptable. Quite the opposite.
(on the other hand there are certainly debates I am tired of, amd frequently ponder how to handle people / situations that bring same tired arguments I've seen rehashed, and usually debunked, myriad times before. But that's not the same as morally unacceptable that's just me being lazy and or having limited time and energy on this earth :)