No need to "hold out"; they're they're for the (FlyerTalk-reading!) public at large:

http://www.flyertalk.com/forum/miles...ey-appear.html

However, the spend requirement on a 50k offer might be much more than for the particular 45k offer he got. (You didn't specify the other aspects of the offer, so I can't tell whether it's just 45k or also lounge passes or also an AA spend credit, and I also can't tell what the spend requirement -- in spend amount and time to do it in -- is.)

Besides, if he hasn't applied for any Citi AA card for at least 20 months, he may be able to apply for two at a time using the "two-browser trick" (read up in the linked thread; read the first few posts and then start backwards from the end after that). Two 40k offers with low spend might therefore get more miles for a more doable spend than two 50k offers with much higher spend. So you have to look at the miles and the spend together, and also figure out if you can afford to try for 2 at a time or not. (And that's 2 personal cards; that's not counting whether you can later try for a 3rd business card!)