As stated above, if the entities claiming to be satoshi but can't provide the evidence by signing a message from the address the first ever block reward was sent to, you can safely assume that you're dealing with an impersonator.

It's so easy to come to that conclusion yourself, but people somehow still have some degree of believe that anyone stating to be satoshi without signing a message can actually be that...

Satoshi's main job is to stay away from anything related to publicity, because every sign of life from him will make it easier for agencies and whatever else to find him. They would love to have a word or two with him, I'm sure of that.