The way I see it, he feels like he needs to prove himself AGAIN, like all he had done so far is nothing. I mean, if you were doing anything for your career and everything you did basically gets put down to very little, and need to prove yourself, I'm sure you would be somewhat pissed about it. Just because this is the fight game makes it no different.
He feels he is getting disrespected by the UFC, that he needs to prove himself yet again to them in order to start making the bigger bucks. Don't tell me that you love this and would gladly take it, because there are lots of people who love what they do, but still expect a pay raise. Or at least don't want to go down in pay, especially if they have a fair bit of accomplishments.
You guys also have to remember that this is a life changing event, he would probably need to move to the US permanently if he was in the UFC, and its not like it free to move your family from one place to another. Getting paid whathever he does, he may feel more comfortable making that then going through all the hassle of coming here for a poor contract.
You say that there will be pay increases later on and all that, but this dude is 31. This is a 4 fight contracts. He isn't getting any younger, why take the risk and go through all that for a measly 20/20 contract?
I find it funny that in this thread, and the other regarding him signing with the UFC, everyone gangs up on this game and saying its stupid not to take the contract. When in fact, you guys should be putting any anger, or frustration towards the UFC.