A few thoughts:
One, it is a sexy story, and reporters are finding those willing to spill the tea on this. Independent of the motivations of the leakers (more on that in a bit), there is a lot of newsworthiness about this (given Disney's outsized place in the culture, and its present position in the culture wars).
Two, Bob I has a titanic sense of self. He fashions himself as someone who could have been president. His autobiography was an attempt to put himself on equal footing with Steve Jobs and Walt Disney. He had much of Hollywood and Wall Street pining on his every word. He has a legacy he wants to uphold, and he gets to do that by reminding people of how much better things would be run if he was still there. Heck, Zenia Mucha is probably dropping this stuff just for fun.
Third, this backstabbing is a little disingenuous because, as the article noted, Bob C is really Bob I 2.0. Bob C appears to have been a loyal foot solider for what Bob I wanted to do. Much of what everyone's complaining about what Disney is doing now are things that were likely well into the works during Bob I's reign (such as Genie+) so all of these complaints shouldn't be placed completely at Bob C's feet.