I dont think your right about any rule change being implemented regarding re-entering the portal after signing paperwork.
The transfer portal in men’s college basketball closes at the end of the day Tuesday. There may be a slow trickle of names that enter in the days following, as
www.si.com
There's an entire section here dedicated to flipping people who have already signed officially with schools, and it says there's a lot less latitude once they're enrolled.
"Still, according to several sources, many programs are actively working to make pitches to players who have already committed to other schools to make them reconsider, often dangling significant raises from the deals they agreed to just a few weeks before.
“‘Committed’ is a loose term,” one staffer joked.
There’s far less latitude to move around once players officially enroll in classes at their new campuses this summer. At least one program SI spoke to had changed their summer report date from previous years in order to shrink the window of time that their portal commits could be tampered with. But until players enroll, they technically remain in the portal even if they’ve made commitments or even signed financial agreements with new schools. Expect talent-hungry schools to exploit as many loopholes as possible to create advantages."