Stolen memes? What an odd concept.
That's what normal people do. This is, in fact, why when Musk posts a meme, that tweet gets thousand of retweets. Ever thought about how if "stolen meme" was an odd concept, then the retweet count would be 0?
Zooming in on both the twitter use case, and how most users of those platforms see meme ~= funny image or OC, a stolen meme is more akin to stealing a joke.
So "stolen memes" is a phrase that makes zero sense for the broader definition of the word meme, but makes complete sense for the more specific definition.