The book states Ulfric took the city and held it ransom until he got what he wanted. Contradicted by Igmund. The book has major trouble providing credible statements. And no the stormcloak rebellion is not the forsworn uprising. Igmund's father died while negotiating with the forsworn(Probably one of Igmund's sources of anger). Igmund states the rebellion started there because it was a rallying point after Talos worship was rebanned and Ulfric arrested.
The story states prisoners were taken and then every single one of them were executed/tortured to death. The fact that Madanach is still alive is strong evidence against the book's claims. It's hard to protest to anyone when you're stuck in prison. I'm pretty sure he even states that he lost all faith in the empire after Markarth. If Ulfric's as "With me or against me" as the story states, there would be no grey quarter, every single imperial jarl would be dead, and he wouldn't have attempted to get Rikke to surrender.
Ah, you're talking about inconsistencies. Yeah, I can see that. Point taken.
There are still a few bits I would interpret differently though.
Like Madanach, the way I understood is that Thonar Silver-Blood stepped in to use and control him, effectively stopping him from being killed. That was done secretively, so if the author of the book writes "everyone" he was probably just unaware of it.
And the conclusion that "With me or against me" from the book needs to imply dead Jarls and no grey quarters seems far-fetched to me

The whole incident was what, 25 years ago? Even if Ulfric wanted to do all that back then, I don't think he had the manpower to execute it or turn his own people against him as a result. People change over time, and he might not be so "eager" anymore when facing Rikke 25 years later.
But in the end I can still see arguments for both sides of the story. So thanks for the input!