A classic Walter Mitty character right there.
He's certainly done his homework well enough to know the broad details of the sinking so he won't get easily tripped up. That was smart on his part, a lot of the fake survivors never bothered to do that.
Mr Hall (or whoever he actually was) was probably a lonely old man just glad to get some attention and conversation. It's quite sad actually that he had to go to all the bother of pretending to be a Titanic survivor just to get that.
As a boy my Dad knew a man on his street who used to tell all the kids wild stories about fighting with the Long Range Desert Group in WW2. Then when the man died my Dad and his mates found out from the old man's family that it was all lies. Seemingly, this man felt guilty about not being able to fight and invented this highly detailed story as a kind of reaction.