I'm not sure whether to read that expression as something menacing or just bitterness over how she's been treated in the proceedings, and I'm inclined to feel the latter and thus experience it more sympathetically than feeling threatened.
I think the main subtlety is « turn against the otherS », plural. One on one squabbling is multiversal diplomacy. Mottom is attacking Mammon because he was the first big target she met on her suicidal run, but she isn’t a real full-wheel danger. Supposedly, the collateral damages they inflict on each other worlds are not so much more bad that what they do their own in time of peace. And it can probably be stopped one way or the other.
Now, if some *unspecified* demiurge were to rush out of there fortress-world screaming "I will kill every ones of you and the Wheel will burn", now that’s a reignition of the universal war and a good reason to act together.