I don't think Dana White has anything to do with this. Other than being the mouthpiece/whipping boy that will have to try to make it sound like a good decision.
The current money people at the UFC did the math and decided he wasn't a big enough draw, it's that simple.
The internet loves Moose, I've loved him since the DREAM tourney, but is he a big draw to the general public? Fighters aren't paid based on their skill they're paid based on how much money they can earn the promotion. Being a better fighter helps that some, but there's so much more to it.
I fucking hate seeing business fuck up the sport I love, and God knows it seems to be the case more and more, but it's been the name of the game from the start. Fighters are going to go where they feel they can make the most money, as they should. The promotion is going to have a ceiling on what they're willing to pay to keep them and it's going to be based on that fighter being cheap enough to keep them in the black on the deal. Bellator is willing to take some of those on as loss leaders to build the brand, they have that Viacom money behind them. It's great for those fighters bank accounts, it's hopefully good for Bellator, but it's not so hot for those of us sitting here wanting to see the absolute best possible fights.
Lorenzo was a bit more willing to bend to keep people because he was so in to the sport itself and UFC was basically his brand.