I have to believe that there were many different shades to Gene Roddenberry as there are to most of us. There is no doubt he was capable of some extreme behavior, but overall the book seems to point toward his being amiable and often a good ombudsman of sorts (as a means towards an end).
What alarms me about who Gene was, and what he seemed capable of doing, was when his ego and greed seemed to get the better of him. With that I point towards the story of Leonard Nimoy needing to get out of work early on Friday and Roddenberry's overt exertion of power. It was as though Roddenberry had forgotten that all people need to leave any meeting with a sense of dignity. Roddenberry seemed very willing to strip somebody of it when his ego wasn't properly placated. Add to that the theory that Gene was the "executive" behind the sordid events that later came out about Grace Lee Whitney, another "stripping of dignity" for the sake of ego, and one comes away with a vastly different perspective on just how far the pendulum was able to swing regarding Roddenberry.
No doubt Gene Roddenberry was the genius behind the concept of Star Trek, and an amiable and experienced man when it came to playing the creative game of television circa the 60's, but he seemed very willing and capable of some dark deeds when it came to gratifying himself, and it didn't matter how much collateral damage was left in its wake.