Ah, okay. Even without having read the novels, I noticed that, but I thought they pulled it off pretty seamlessly. Just moving forward to a new stage of the larger story arc...I don't think ITDUDE meant "reboot" in the sense of altering the continuity, just in the sense of ending one story arc and starting a different one midseason, which The Expanse did in both its second and third seasons. The break between the stories of the first and second novels took place midway through season 2, and the break between the second and third novels fell midway through season 3, with a time jump between one episode and the next.
Without haggling over the distinction between what it means to affect "fan vernacular" versus what it means to be "broadly popularized," I'd say the usage goes way back before nuBSG. Perhaps that's because I'm a comics fan, and major comics publishers have been doing "reboots" in this sense since at least the 1980s. Insofar as TV franchises got into the habit later, they merely borrowed the usage, they didn't invent it.I believe that the term came to be more broadly popularized by the Battlestar Galactica remake in 2004ff, and since that particular "reboot" was a complete reinvention of the premise with no continuity with the original, laypeople got the mistaken impression that the term applied exclusively to a continuity reinvention, and that's the meaning that subsequently came to dominate in fan vernacular...