Okay well that I could understand.

I did mention he hid himself, albeit indirectly. It knows it cannot do things so obviously, and has primarily targeted low-tier supers who wouldn't cause a hullabaloo during a fight. Minimize the obviousness of his actions, so to speak. After the deed is done, he goes back into hiding, waiting for the next target to be decided and the opportunity to arise; he wouldn't do such a thing in the middle of a busy intersection.

What if I made him more human-sized and gave him a cloaking field? Would that make it more plausible? Of course I'd have to change his backstory such that it doesn't involve time travel, cool as it is.