"Effective immediately" is harsh even though perfectly legal. Does this mean nobody knew and it was a "Surprise!!!"? Extremely callous if that's the case, there is got to be more to the story.

Is a CEO really worth 20% of market cap? Nuts.

It looks like that phrase was removed from the article, but that is standard for C-level jobs. When you resign, you're shown the door immediately. The same thing happened with Marissa Mayer when she left Google during a phone call. Call was ended and her accesses terminated. Can't risk any additional trade secrets leaving.