If you vote for team A and they win and then do something bad (inevitable), shouldn't you be morally responsible for that? After all, you seem fine claiming non-participants have moral culpability for whatever the winning team does.
This seems incredibly obvious. If my options are "don't bomb children" and "bomb children", there's an obvious choice and obvious culpability. If my options are "bomb children" and "bomb way the fuck more children" the choice is also obvious.
You do not get to pretend a moral dilemna doesn't exist just because you're not a fan of the available choices. You are still culpable.
You have a train hurtling down the track that forks into two groups of people, 10 in one and 5 in the other, some of the people go on to cure cancer and some are murderers and you don't know where they are. Also it's possible batman set up the scenario to kill the bad guys and by flipping the switch you kill the good guys. Or the Joker set it up and the reverse is true.
In this case, you could argue that you only have moral culpability by intervening. Unless you are absolutely sure you have full knowledge of the intended consequences by acting, you can absolve yourself of the moral culpability by non-intervention.
And since we don't know the long term consequences of political actions, there is at least an argument for non-intervention.
Fortunately the Czech president does not have that much power.
In general, I believe that more choice is good and polarizing political systems are subpar.
There are just two possible outcomes: Dems or Reps getting power. That's the switch options you have. "Not Voting" simply means letting the trolley take the Rep route and being JUST AS CULPABLE for the results as every single republican voter.
Your fantasy of "not voting" being an actual moral option is like arguing "I disagree with the concept of a trolley, so I'm just going to turn away from the switch". You're morally exactly as culpable, because you made a choice that is morally the equivalent of "not switching tracks".
Voting for party A/B is a reward that encourages party A/B to do more of what they're doing.
So let's say only 1000 people voted because everyone else hated both options. That would pave a path for party C that would not exist if everyone held their nose and voted for crap.
That's your choice. "I don't participate at all" doesn't work unless it makes the whole trolley go poof.
As the eminent philosopher[0] opined:
You can choose a ready guide in some celestial voice
If you choose not to decide, you still have made a choice
You can choose from phantom fears and kindness that can kill
I will choose a path that's clear, I will choose Free will