But this pretends that "not voting" is somehow a morally neutral inaction. It is a choice, the choice to support genocide EVEN HARDER.
This has very little to do with utilitarianism or deontology, and everything with retaining a feeling of moral superiority without having to actually do stuff.
You want a deontological take? Start bombing bridges or other infrastructure. Stop paying taxes, go to jail. Do literally anything that doesn't amount to "not doing stuff makes me better, akshually".