>>4339838It's not so much as seeing a swastika and getting upset, I think it's more about ascribing extreme political beliefs to characters that have shown no inclination towards anything of that nature.
I think two key factors are how much/how you value the characters. If you see them as just vehicles for your entertainment, then you probably wouldn't mind seeing the character become something they're not written to be. But if you value them as their own person, with their own unique personality, beliefs, emotions, and values, then you probably wouldn't want to see their representation distorted from how you know them (how they're written, how they are).
The other is how likely that character is to exhibit those traits. Anime is an incredibly diverse medium. You have characters like Esdeath or Tanya, for whom it's not much of a stretch.
But then you have characters like Mio or Bocchi, where it's very inconceivable that they'd be into that, and representing them as such is a significant distortion of who they are.