You think? Would you take Leno's word on any of this? Like others said, read up on his past history. When it comes to business, he is clearly not the person he makes his persona to be. My guess is NBC knew Leno was going to cause problems so they setup contracts to make it clear that they were going to move on, hoping to not repeat what had happened before (and figuring that transitioning between two very successful hosts should go smoothly). Then, Leno made a fuss, and NBC, worried about having just booted a #1 rated person, thought they would be able to appease him and get some good ratings so they agreed to let him do another show. If I'm not mistaken, it started out as a different show from how Leno did the Tonight Show, but then Leno changed it back to doing his same old shit at a different time. When Conan's ratings tanked, Leno saw blood and probably went after him.
NBC thought they were going to look less stupid bringing Jay back. Hell, I wouldn't even lay the blame all on Zucker, as he probably thought, hey this will make me look smart by getting Jay back on the air. The problem is they royally fucked that up, and it royally fucked everything up.
I see them reference the cost of Conan's poor ratings and paying him off. How much did Leno lose them with that new show? Factor in how much they fucked over their affiliates, and this has probably done damage that will take years to clear up just on that alone, even completely ignoring the Tonight Show. In fact, between this and the Olympics, NBC might have lost half a billion in roughly half a year. They panicked and just dumped what were long term investments for them. They might have tried to minimize the immediate losses to look better for Comcast.