Well I mean, how does it affect you if he is lying, its really none of your concern...
Just look at it...
This mod: 1 person claiming to be making a mod, and has nothing to show. Broken description, etc.
Fallout 1 remake: Multiple people working, multiple testers, multiple people can verify, it does indeed exist.
See the difference? Unless the Fallout 1 remake is some grand plot to take over the forums via a well planned scam, it is safe to say it exists. This on the other hand, we only have the OP's word.