This move benefits Harden. He will in all likelihood start now, rather than being the 6th man, which will most likely mean increased stats a little bit. Even if he doesn't work out a deal with Houston for a long-term, it will mean someone will give him a max contract based on his stats next year. He is a very good player, but his stats will be padded because he plays on a "so-so" team and someone out there will bite and give him max based upon those numbers.
I personally do not think the guy is a max player. When you say max deal, you think of franchise players, game-changers, guys who can decide the fate of a game on their own...I just don't see this guy as one of those types. He is a very good player, but he isn't a Kobe Bryant, a KG, a Durant, a Michael Jordan, even a LeBron (yes, I said it...He earned it 100% last year)...guys who can take over a game at will and just leave the competition at their mercy.
I could see him being along the lines of Joe Johnson...Good, good player but not really worthy of a max deal...Not a true franchise player, but they somehow sucker a team into investing in them for the max.