Guppies will pick at algae naturally, at least mine do. They eat anything they can find. My gups LOVE black hair algae, too bad they pick at it but don't seem to eradicate it.
I think, if I were you, that a new tank would be underway soon. Those guppies need to go somewhere safe! It doesn't seem like it's working out with those tankmates. I have two betta tanks, and I always treat them like betta only tanks...if there is any shred of aggression, tankmates are removed immediately, because you just don't know what will happen.
Also....that Hitler analogy was a little...well...harsh. Kinda made me cringe a little. Maybe use another one next time? I know you didn't mean anything by it, though, it's just a tough thing to read, yk?