Eh, I wouldn't say that. Canon Homunator...really didn't become all that amoral. She is really ruthless, and she is willing to kill her friends if she thinks they're going to lose their minds or Witch, but...well, we all remember Tetris.
She's just trying to get a Good ending, not a Golden one. A few dead friends...seems rather like an inevitability by the time the main Canon timeline comes around. Who kills them probably seems pretty trivial to her, and stopping them from ruining the loop is worth some bloodshed.
Amura? Amura's a cat. Her mentality is not much more human than Kyubey's own, as we've seen already: Once someone is prey, they stop being a person to her, as we saw with Catnip Cat and all the fucks that weren't given over killing her.
There's a reason we only keep very small cats as pets: They can't accidentally/unthinkingly kill us when they decide to play.
Amura, instead, has magical powers and can grow to a truly massive scale.
I really hope Madoka can keep this kitty on her best behavior.