The obvious and played out rebuttal to this is the lesser of two evils argument. I refuse to participate in a system where the lesser of two evils is voting for any politician actively participating in genocide.
@Hunter problem is, you live in such a system. It’s a cliche but nonetheless true that "refusing to participate" is equivalent to voting for already-established power.
I feel the pain! I'm not yet a Dutch citizen and so cannot vote in national elections. But for local ones, I enjoy the freedom to vote for minor parties that best express my ideals, without fear of throwing away my vote.
But, remaining a US voter, I still have to choose between far less desirable candidates or simply throw away my vote to "make a point" that will be heard by no one. :-(