Where is that information confirmed? Why would Boon expressly hint towards GGPO if it's not that?
In the announcement video. They make a point to say "similar in function to the GGPO model" and it sounds like they are developing it themselves. To use GGPO they would have to license it.
People use GGPO as a shorthand for rollback-style netcode because it's one of (if not THE) innovator of it. GGPO is a brand. It is to rollback netcode as Q-tip is to cotton swab.
Boon might not have thought too carefully about implying a specfic brand.
If I were the GGPO guys, I probably would be a little irked, especially if it turns out bad and people think it's GGPO.