So the true answer to what would it take for me to not vote for Biden was “nothing.”

For me yeah. I’m just saying I sympathise with all those who think Biden crossed their “activation energy” line by supporting Israel’s genocide for this long.

what would it take to get you to cast a valid vote for a US democrat president

A good track record. I’d want to vote for Bernie if I could, after hearing the fire in his voice and knowing he means it.