[There's the briefest hint of a frown before returning to neutral once again, perhaps putting out all the information would have been better. But some of it hardly seemed necessary...]

Because Umbra are the ones that are formerly entitled rich kids, more or less. They still act in the same ways they had when they were human, they would easily stab us in the back if given half a chance. Or that's the feeling I get from them from the descriptions. While one is basically the Russian mob, they can at least understand what a truce does for them and won't do anything that would tie themselves to a murder, those types are very keenly aware that attracting attention isn't good for them.

And, well, the Beach Bums are honestly about the same in not wanting to draw attention to themselves.

Basically it makes Umbra the unpredictable element of the three and, honestly, I am not a fan of that element.