No loophole. The SEC & Big10 went from 14 to 16 teams after the initial steering committee with Bowsby, Sankey and I believe Swarbrick announced the proposed 12 team Playoff format in spring 2021.
The Big12 after losing OUT didn't stay at 10 teams, bumped up to 12 teams.
The Pac12 is looking to add SDSU & SMU to get back to 12 and in recent days media reports have cropped up mentioning Rice, UNLV, BSU. I would be surprised if the Pac12 makes many friends adding 4 teams, but they are fighting for their survival.
Plus the "loophole" only works if ESPN, Fox, Amazon, CBS, etc are willing to pay for the additional inventory as part of their Media Rights deal.