The problem is other QBs in the portal will have a month head start in the transfer process, and by waiting until after the bowl game, there may not be as many options. Maybe they should open the transfer portal the day after the CFP championship.
That would make sense from an athletic standpoint, but it's likely not workable from an academics standpoint, assuming players want to be at their new school for the spring semester. The CFP final is Jan 8th this year, and first day of Spring Semester starts Jan 16th (at ISU, anyway). In that week, players would have to announce they were entering the portal, schedule and take visits, figure out NIL deals, pick a school/team, get enrolled in classes and move. That would be a nuts schedule that's practically impossible for everyone involved.
IMO, it is what it is. Maybe they could start the season earlier, but that would mean games start before classes for the fall semester. They could cut down the regular season, but that means less football. They could move up the Bowls and CFP, but unless they move off of New Years day as a big day for college football, they're really only getting another week for the portal to be open.