What should we do about him? On the one hand, if we take him prisoner or allow him in on a probationary basis (I doubt the latter is likely, this is just hypothetical) then at least we'll know what he is up to, and the probability of him causing further damage is lessened.

On the other hand, if we turn him away, he is free to run amuck, and we will have even less control over him.

Quite a paradox.