I'm sympathetic to your point. But ultimately I gotta disagree with the premise of your argument -- specifically, that the misery of being a cuckold makes the use of the term "cuck" unacceptable. Much to the contrary, I think that it makes the term /suitable/ for many situations -- situations that are, in some way, emotionally analogous. I'm hesitant to make this claim unequivocally -- I can see arguing that the mechanics of the use of the term "cuck" exceed mere metaphor in objectionable ways -- but I think that the ability to speak directly to emotional reality supersedes any such argument.

For the record, I'm not defending the alt-right in any capacity. They're loathsome fascists. And that's key -- the problem is the content of their positions, not the language in which they're expressed.