Ba'al gives a slight raise of an eyebrow when he takes his shirt off in front of him. While he hadn't expected him to, it's telling that he is.

"You realize, with the amount of blood you left in my car, it would be astonishingly easy to fake your death." Said while Mike is in the bathroom but loud enough he can hear. "Should you wish to avoid creditors." It sounds like a joke(it partially is) but it has a faint undercurrent of threat. He could easily make the world think he's dead while having him locked away somewhere.

Yes, he could actually kill him and leave him dead but where's the fun in that.