Well, the uncaptioned memes were intended to create a record of how much of my time he was wasting. Eventually, I stopped posting them and hitting the delete button only but his spam kept coming.
I discovered it is not actually feasible for a moderator to deal with a spammer who is persistent enough.
I concluded unfeaturing the meme was the only way to deal with it.
This was a pretty relentless and egregious attempt to derail not just that meme but the entire stream.