[Eldar14]

I think it does mean 'held' in a literal sense of having the rings in his actual physical possession, but more of still knowing the whereabouts and having power over. He didn't know where many of the dwarven rings were, so he did not 'hold' them, and he no longer had power over the elven rings, so he did not 'hold' them. However, he still had power over the nine rings given to kings of men, and so he 'held' them.