You could campaign for a 3rd party to outright win, but you risk splitting your less-hated party’s support. This isn’t hypothetical either, it’s how we got George W. Bush.

This isn’t an entirely factual claim, and I do have an issue with the way you’re framing it. First, the facts:

• Not everyone who voted for Nader would have voted for Gore, or would have even voted at all;
• Gore probably won anyway.

So, it is an entirely speculative claim to say that Nader spoiled the election for Gore, and it is a scapegoat the Democratic Party uses to sway people from voting for candidates who would better represent them.

What I think is more important, though, is that it is deceptive to frame this as the fault of the voters. The blame rests on Gore himself for not being a better candidate. Gore needed to appeal to third-party voters, but didn’t do it. That is not their fault, nor is George W. Bush their fault. If you want to blame voters for George W. Bush, you can only blame the people who voted for George W. Bush. Even that is dubious, because Republican voters, just like Democratic voters, have a major problem when it comes to their candidates: they are all pre-approved by the same oligarchic elite. The blame for George W. Bush rests entirely in the corrupt two-party system that made him a viable candidate in the first place.

I agree with your assessment that voters in non-swing states should vote for third-party candidates if those candidates better reflect their values, because we will never eliminate the failed two-party system by voting for Democrats or Republicans. It is, thus, a moral imperative to not vote for Democrats or Republicans anymore. I just differ from you because I don’t think this should be limited to non-swing states. I don’t think you should be privileged to vote third-party just because you don’t live in some place like Florida or Ohio. Every voter in every state should feel totally fine about voting third-party, because it’s the ethical thing to do no matter where you live.