I've read a dozen articles on this from a lot of sources, and the best I can gather is that Mary Hulman and the evil sisters, wanted Tony George to stay atop IRL.
But Tony realized he'd be left to run IRL and have to run constantly to the Estrogen group for money that wouldn't come and he resigned. He'll focus on Vision Racing and his other business interests.
So two firings, and a walk away. Some reports say TG spent a half BILLION on keeping IRL alive... Sisters are pretty pissed off about their yacht money being flushed down the drain.
Dr. Conemangler
aka The Malefic One
2015 Wildcat Honda F600