It's true, and I also know a lot of old-school conservatives who believe every living Republican is basically a libertarian and that the last real conservatives died in the 19th century. I don't know if they vote, but if they do they're inverting the paradigm and making the best of a bad situation by voting Republican. Goes both ways. However, that's not a full justification for abstention -- the more powerful argument, in my opinion, is that past a very localized point, an individual's vote simply doesn't matter. Mathematically, systemically, etc. In the situation you outline, if my vote mattered I could still express my value scale (assuming one candidate was even slightly less bad than the other). Unfortunately, under the current system that won't help my vote count.