I wasn't aware of any such rejection. Nor you, nor a google search, nor my local library can find any reference to such a rejection. Furthermore it's easy to find fatwas agreeing with this. Care to point out at least one paper (that isn't on an obviously political site) ? To be honest I've read the sources on the story and several of the others and I'd find it hard to believe.
And what about all the other ones ? It's not like executing people for criticism is something islam's prophet did once. Well, compared to the thousands of people he ordered executed (e.g. the massacres he ordered around Mecca) it may not be that much.
This is not a sweeping statement about a religion. It is a simple statement of fact. Just because a statement is currently policitally inconvenient or "sweeping" doesn't affect my opinion of it at all. As you very well know, there are far more damning sweeping statements one can make about islam that are equally true.
Frankly, islam was created through a protracted and bloody war. Everyone, including muslims, agree on this. Do you find it all that surprising that atrocities happened on both sides ? The problem I have, of course, is that one side claims to be the definition of good, and went on to commit massacres elsewhere in the world on a scale never seen before.
Why do you feel the need to reject historical fact ?