a lot of the arguments against third-party voting are arguments against voting in general.
Maybe. But with the system in place a vote for a third-party candidate is effectively an abstention. I think you're right that they're more politically considerate and wanting to make a difference. It's the desire to make a difference and effectively abstaining that seems incongruous.
Sure, but one side seems to be advocating for more of the same shittiness we've had for decades, and the other side for a final solution to the Palestinian problem. It's not like the choices are equal.