Your principles are sound, but not voting in any election is imo equivalent to voting for whoever wins. If that turns out to be Trump your moral high ground has no basis because you actively enabled that result.
Voting for a candidate doesn't have to mean endorsing their entire being, it can be for many reasons, most noteably tactical voting to ensure the least bad outcome.
This isn't a matter of disagreeing with this or that policy of a candidate. This is genocide. I don't need to agree 100% with a candidate to vote for them, but I do have a limit and if anything exceeds it, it's genocide.
Whether you like it or not, refusing to vote for "less genocide" under FPTP is a step towards "more genocide".
I get the sentiment, nobody likes what FPTP has done for our options when voting, but refusing to play the system isn't the grand stand you think it is.
I refuse to participate in a system that forces me to choose between two genocides. There is no victory worth giving political backing to a genocide. A system so evil cannot be redeemed.
Not voting is still participating in the system because you live with the results, sorry mate. You don't get to opt out then absolve yourself of guilt from the result if its the worst case.
Oh I'll still be guilty of paying taxes, and of not doing more, but I won't be guilty of voting for a genocidaire. Call it a boycott, call it conscientious objection, call it whatever you want, but I won't sign my name to a genocide.
Choosing the path that makes more death more likely while claiming to want no death...yeah, that's moral grandstanding.
I get that it's a real-life "trolley problem" situation, but it really isn't that complicated. It sucks that the lever only goes two ways because of FPTP, but you're not a more moral person for refusing to touch it.
If you actually care about people being killed, then join the movement against the FPTP system so that in the future "no genocide" will be an option, and in the meantime exercise your ability to save lives.
It's a trolley problem, except we are currently running over thousands of people, and we are still months away from the switch. There's a guy in power right now, who could stop this, and he needs our votes to win the election. I want more pressure on him before the election, since all leverage is lost afterwards. You want to assure him of our votes, which means he has zero political reason to stop abetting genocide. Don't you see how by saying "blue no matter who" you are stabbing everyone in the back who is trying to halt this genocide? We know Biden doesn't mind murdering children, so our only hope is that he actually wants to win the election. In order to leverage that power though, he needs to realize that voters aren't guaranteed to show up for him.