Since it refers to themselves, the reflexive αὑτῶν (=ἑαυτῶν) is in order, and I would expect that to be editorially preferred. But I’m not sure that αὐτῶν can positively be said to be wrong. The manuscripts are unreliable in such matters, and there’s often inconsistency among editors.
Many thanks, Michael. I will think exactly that. From this work, it was nice to learn that ἑαυτῶν is sometimes spelled αὑτῶν. Now if I can just remember that!