The point of red lines is to not cross them. If you consider supporting a genocide a red line, which is certainly what I was taught, that means the system has moved beyond the pale and you must now take a different approach to politics than the horse race lesser evil logic that you were taught by the ruling class.

Namely, start working on other ways to build political power. The other ways are actually stronger. The ruling class, logically, teaches you to only see politics through a lens that disempowers you. It gives you playdough when you need a knife.