Reject and delete with rejection reason:
None of this will work in this scenario.
You can't "do nothing". It leaves you with a clutter.
You know he's a spammer, so "approval" defies logic.
That leaves "Rejection and deletion", which is fine, but still leaves you short because you should ban this person at this stage to lock the email address in your dungeon forever. Merely rejecting and deleting leaves room for him to return with the same email address.
Let's say you visit his profile page within the Admin area to ban him there, which works brilliantly. He's still on the awaiting approval list though, even after you have banned him elsewhere, which still leaves you with only the troika of options above...
Long story short: can a 4th option - Ban his behind - be added to the Awaiting Approval page? Or is there a work-around that is not cumbersome?