The manual to MM1 states that Gutsman controls the miters and aids in the construction of the various buildings and the like...
Either that, or it's from the Anime...
But regardless if it's from the fans or from Cap themselves, Capcom now endorses it... or at least did at some point, I'm sure.
Also, a bit of trivia: all of the "men" from the first game are actually jobs:
Iceman: A few possible references... To "ice" someone could be to kill them, so an assassin is an iceman. Before modern refridgeration, people bought huge blocks of Ice that people brought into homes with those huge tongs. Also, it could be an allusion to the "Iceman" that's considered the oldest discovered human.
Fireman: Straightforward, huh?
Cutman: This is the title for those people who, during boxing matches, quickly patch up the boxers, since bleeding on the mat is grounds for the loss of a match.
Bombman: Two possible. Demolition crews in the war were headed by the guy who actually primes the bomb, the "Bombman". Also, it could be the "fall guy" that a lot of different groups use to avoid the law.
Elecman: term for people who run petitions for elections, but I doubt it's this one.
Probably shorthand of "electrician man" if it is indeed related to jobs.
Gutsman: The signle strongman in a group... named for their appearance in WW1 where they moved the corpses away from the hospitals.
This is not my bit of writing, so I apologize if it's wrong, but I do know that cutman/Fireman is accurate, and that Iceman is indeed the nickname of the guy who they discovered in that cave >_>
I'll try to be less specific next time ^_^