^^^ This.

It's so situation specific with Citi. I have a personal Citi Executive card that started at 60k credit limit and is now 250k credit limit, so I assume it goes much higher for business versions of the card. They are pretty good about raising it when you ask, but you have to really use it. I am hub-locked and most of my flights are on AA so it makes more sense for me (probably still not as good as a 2 percent cash back card but I do get real value from AA status). If he doesn't fly AA much, I would not even bother.