I agree banning might be a little much over this, but I would like to see roll backs happening. Like others have said, sure, levels mean nothing - but this sort of thing happening means that if levels ever do mean something, whatever that reward is gets devalued by people having abused a glitch.
Not rolling back is pretty much sending out the wrong message to people. Yes, other things are “more important” but this shouldn’t be a huge thing to do, just to echo this:

