HunchBluntley: No. Only a Blue can do it.
tinyE: then a blue came in here gave him credit for answering his own question? :P
More likely one of them (staff member or OP) decided it would be good to mark the thread as solved, and figured that, since it was solved behind the scenes, they might as well just mark the OP as the solution. Notice that, since it was marked "Solved" manually, he doesn't seem to have gotten the usual rep boost.
I'm sure they just wanted to make it clear at a glance to anyone who'd been following this that the mysterious exploit vectors were fixed.