You’re playing semantic games to avoid believing/saying that you’re supporting fascism

I don't think it's semantics, I think there is a very clear distinction.

There is no “voting against” only “voting for” (in this context, obviously- for the presidential race)

I disagree, when only 1 of 2 outcomes are possible, choosing the preferable one is not a complete endorsement of everything they represent.

but I don’t believe there is a “right” or “wrong” with this

Why not? If you value harming less people, how is the "right" choice not the one that harms less people?

I enjoy these kinds of discussions as thought experiments, but there’s a time & place for it (and this thread isn’t it, imo)

It's not a thought experiment though, it's the possible outcomes of the election: D or R.

abstaining and voting third party are both valid options

Not if you want to actually influence the outcome. See, you're engaging in thought experiments, I'm talking very pragmatically.

Other people, like myself, prioritize long-term consequences, principles, etc. over immediate consequences.

Long term consequences such as what a worse administration could do for 4 years? Like all the climate goals that got immediately revoked, is that long term enough? There is a long term impact to letting the greater evil win. How are Republicans better in the long term?

but it’s dishonest to try to absolve yourself of culpability with semantics.

Well at least we can agree on that. Abstaining and voting third party are objectively valid options, as in you are not literally forced to pick between only D and R, but that's semantics, because there are only two outcomes.

I think if your "principles" include less bad things happening, they wouldn't prevent you from choosing the less bad outcome. It seems to me like your principles are more about purity