Very probably. Joël was a legend - almost as much so as Stefan. Although I wouldn't be surprised if it was "invented" by a number of people independently, and Joël was just one of them. I suspect Stefan Pochmann knew it was potentially a practical method as well, as did several other people.Did that guy just invent 3-style three years earlier?
Right after 3-style actually caught on, there was some talk about the possibility of using 5-cycles instead of 3-cycles. Wouldn't it be interesting if someday 5-style actually became a thing? To make that possible, the big challenge would be to get where you can "see" how 5-cycle algorithms work, much as people currently "see" 3-cycles in their head now. I wonder if it's possible to do that generically?