Joe Biden is "only" Genocide abroad, and probably less of it.
Therefore, a vote for Joe Biden is a Vote against genocide.
No, it's a vote for genocide, but less. Still the right thing to do of course, but I'm sure you can see how that is still a vote for genocide. No need to twist yourself in knots to justify this, it's a vote for genocide AND the only sensible thing you can do in the current American political system.
Personally I can understand how this doesn't sell people on the idea so well. Maybe Biden just shouldn't do that