AA sets the value at 2.5 not Citi. Citi used to offer 40k and 25k promotions for different types of checking accounts, and those are the ones that hit in 2011 and are getting 1099s now. In begining of 2011, Citi marketing realized this and the potentially disastrous PR and stopped launching offers over 24k (that's why 23,500 was the offer in the 2nd half of last year lol).
As far as class action law suit, the T&C always said "customers are responsible for taxes, if any." - so there goes that. You've been warned.
They may go back to raising the offer over 25k, look out for a 30k Citigold offer in your citi credit card statements, february e-mails and a direct mail in march or april (if you don't have a checking account), with better, clearer language in t&C (maybe something like... "this WILL generate a 1099 MISC and be reported to the IRS").