There are conflicting reports about whether the fight will even happen. Cesar Gracie, who manages Diaz, told MMA Junkie that the rematch is not happening.
However, the fact that Condit even agreed to it in the first place is a ridiculously shortsighted move on his part. You have to appreciate his fighting spirit and willingness to put his match with Georges St-Pierre on the line, but he is risking a lot by doing this.
Condit has his unification bout with Georges St-Pierre, who is expected to return from a torn ACL later on this year, set. He can stand toe-to-toe with the best welterweight fighter in the world to determine who is the one true champion.
In addition to being able to fight for the undisputed championship, he is risking a lot of money in the process. St-Pierre is the biggest draw that UFC has now that Brock Lesnar has retired.
Shows that St-Pierre headlines do well over 800,000 pay-per-view buys. No other fighter in UFC comes close to that level.
Condit's payout for a main event fight with St-Pierre would be significantly higher than any amount of money he has received in the past. He is not a draw on his own, so he needs all the help he can get selling shows.
Condit and Diaz did have a close enough fight at UFC 143 that a rematch makes sense to determine who really is the better fighter, but Condit stands to gain nothing by doing it. He will get respect in the mixed martial arts community, so if that is what he is looking for, then more power to him.
In the best interest of his career, a rematch with Diaz is a mistake. He might win again, and if he does, this argument is moot, but you never put the biggest fight of your career on the line against someone that you have already beaten.