The criticism of Stern came from an 'anonymous' source within the Hornet organization who leaked that the trade to the Lakers was done, and that the league had approved. At that point, Dan Gilbert wrote his letter to Stern, and supposedly the NBA and Stern reconsidered the deal and stopped it, with three different reasons for doing it within the first hour.
So, the story from the source was that Stern acting as the NO "owner" was a cover-up, because the league had approved the trade prior to some other owners objecting to it. Hence, the reason the deal was killed was because of other owners, and not Stern acting as an owner.
Stern is a very skilled lawyer, and I certainly wouldn't take anything he says at face value. There is at least some smoke to this story, still, no matter what spin Stern puts on it now. Without the NO source, I'd be willing to believe Stern 100%.