The greater of two evils will accelerate the exact same genocide in question (Gaza) and enable genocide in other areas, e.g. Ukraine, and possibly Taiwan in the future if and when that situation escalates. This is not the argument to make, unless you’re intentionally arguing in bad faith.
For a Trump presidency, do you mean a civil war happening during WWIII? Because that man wouldn’t do jack shit about stopping that from happening. He’d just join his buddy Putin’s side of that conflict, supposing the civil war resolved in his favor. And supposing WWIII’s nuclear Armageddon ending isn’t reached before that point.