All stuff they posted prior to shutting down pointed to this NFT not being a joke to be honest. Seems like their claim that it was a joke is more about damage control than it being true.
So without knowing more than just what is written in the OP: when I read in the same paragraph that "we didn't get to the point of selling" and "besides, it's just a prank bro"... yeah, clearly. Could be true, I suppose it doesn't really matter now, but I'm not convinced. I also read it as trying to save some reputation.