Assuming you do believe that genocide is extremely shitty, wouldn't that imply that defense of (actual) genocide, or the principle of it, is in all likelihood shitter than a false accusation of genocide? Otherwise I think you'd have to claim that a false accusation is somehow worse than the actuality or possibility of mass murder, which seems preposterous if you have even a mote of empathy for your fellow human beings.
As others have pointed out, the fact that you would like to make light of cities being decimated and innocent civilians being murdered at scale in itself suggests a lot about your inability to concretize the reality of human existence beyond yourself (lack of empathy). It's this kind of outright callousness toward actual human beings that I think many of these so called "rationalists" share. I can't fault them too much. After all, when your approach to social problems is highly if not strictly quantitative you are already primed to nullify your own aptitude for empathy, since you view other human beings as nothing more than numerical quantities whenever you attempt to address their problems.
I have seen no defense for what's happening in gaza that anyone who actually values human life, for all humans, would find rational. Recall the root of the word ratio—in proportion. What is happening in this case is quite blatantly a matter of an inproportinate response.