That maybe how you play the game, but personally I like my players to do things in game that actually reflect their learning. They can't get forbidden knowledge xenos if they've spent the whole game chatting up prostitutes in a brothel downhive.
That's also how the rules suggest the game to be played - as long as something is on your advancement chart and you have the XP, you can get it. Detailed explanation is reserved for Elite Advances.
In this regard his argument makes perfect sense. Money is nowhere near as restricted as experience, whether ingame or in reality. It is far easier to rationalise getting 100 million dollars in an RPG than receiving 50,000 XP all at once to advance your character (although still possible depending on the setting).
In reality? Perhaps. In game? Characters usually gain their allotment of money every month. On the other hand side, during that time they may get no XP at all (no games played while the characters are in warp transit) or around two thousand (about six sessions à 300 XP with a climactic final for a few more). If you want a "realistic" system, abolish XP and use learning times.