The only "evidence" we have to the contrary is a few frames in a video showing him on a computer screen. Why does that mean he's a computer? Even if it hadn't been for the AI character in Fallout 3 I wouldn't jump to that conclusion. By that logic anyone that does a video blog on YouTube must also be a computer.
The thing is, (like I said in another thread), Morpheus in Fallout 1 had video footage of himself playing on the walls of the Cathedral. It didn't mean he was a computer, it was just that the whole thing was a little Orwellian.
For example! http://www.comedycentral.com/videos/index.jhtml?title=planex&videoId=162976
I guess Mom's a robot too.