Not plausible or believable
One hears such improbable wonders about you.
It is improbable that he meant his order to be literally executed, it is not certain that he knew they had taken the oath of allegiance to him.
It is not improbable that these chapters are based on an earlier Jewish writing.
But it may perhaps be considered improbable that organs like the wings, having once been lost, should have been reacquired on the large scale suggested by the theory just put forward.
It is not improbable that he was in fact an hereditary chief of the Basques, but no contemporary records exist.