This is where gaming statistics and character background sometimes diverge. I agree totally that Marcus was a worker, but he also had military training. When I wrote him up, I realized that if I made him worker first, it would hamper his total combat ability (which, honestly, is one of the highest in the show). On the other hand, if I made him soldier, his show-given abilities would stay intact as the small sacrifice of potential work skills he never uses and may no longer even remember well enough to put into effect. That's the option I went for.
Remember, a character does not have to be modeled after every life experience they ever had. If that were true, high school would require all of us to take at least one level of Expert (from the d20 SRD) to simulate those skills we were supposed to have learned.
Some may not agree, but at least you can see what I was going for. That help any?
-August