Now let's look at it this way - a rogue is generally a very precise class, one that requires a great amount of skill, practice, & concentration, while the barbarian is a wild, very enduring class based almost entirely on survival.
Now, both of those are generalities, & there are exceptions to the rule in all cases, but let's look at it this way -
Generally, one becomes a barbarian by entering into a warrior class, but because of inability to control their rage, they were unable to advance in fighter levels, & began learning how to combat on their own, or by just living in a rather secluded manner, learning personal inner strength over practical fighter techniques.
Now, the rogue class is something that someone must practice very heavily. Something that requires alot of attention, & generally someone to teach, or at least a good deal of people or things to practice on. I really don't see that many instances where a Rogue would be a Barbarian, as a Barbarian probably would have the concentration to become a Rogue right away, & a Rogue probably wouldn't have the strength or need to look into combat that a Barbarian would.
Now, an apprentice level is generally understood that the person has become an apprentice, learning from someone else who are teaching these skills. Now, I really cannot see anyone really every being an "apprentice" Barbarian, as I don't see how the skills of rage & primal battle to really be able to be taught. And like I said, why would someone who was becoming a Barbarian become a Rogue at the same time, & how would they be able to justify the concentration of both classes?
And as the person said, this guy obviously lived with Barbarians, so where did he become an apprentice for a Rogue at? And what Rogue instructor would live around Barbarians.
This is obviously (and was stated as) a power-gaming issue where the player wanted nothing but more abilities.