He's a soldier in the mutant military.
I wonder if that was during Robinson's brief run on the book when he fought Conquest? Seems vaguely familiar. May have to go back and re-read. I did love how Cable beat him, though. Taking him back to prehistoric times and setting a trap. Good stuff. Cable is basically Batman with more upgrades (mutant powers, cybernetics, time travel, etc.).
He is a soldier despite growing up soft and pampered by Redd and Slim. Hope had a much more military upbringing.
As the son of two of the most important X-men in history, who were afforded the ability to go to the future for years to raise him, Cable's privilege is clearly showing.