Yes, but that's the point. I don't argue that his execution was undeserved. I say that keeping him alive--and permanently imprisoned--would have served the same purpose, i.e. punishment, deterrent, and perhaps revenge, but would have kept those tales available. They might have been important. Their loss serves no purpose.
He should not have been executed--not because he was undeserving of it but because he might have proven useful if kept alive, and permanent incarceration would have been about as effective a punishment as execution.
How would he have proven useful? I don't see any incentive on his part to provide any information once he has been convicted and sentenced, one way or the other.