My reading of that line was always this:
Eddie is sort of a wounded, old animal at the end of that scene. When Amos says "Hey, I need to ask you something?" in that earnest sort of way, he gives Eddie the fleeting impression that he's going to ask him something respectful, something such as "i know you were great... can you show me how to break better/hustle better/go on the road/etc". Eddie would then at least have the comfort that although he lost, Amos was respectful and possibly even knew he outran the nuts during the session.
Amos knows all this, and wants to stick the knife in even further. So he sets up the question in the above way, only to ask him something he'd just as soon ask his grandmother (about the weight). As if telling Eddie, "I know you thought I was going to ask you something related to your expertise of the game, but you're about as useful to me in that respect as some stranger off the street."
It's a rather devastating blow.
- Steve