The transfer portal should have been specifically designed for players like Cam Sullivan long, long ago. Guys who paid their dues, aren't going to the league, could maybe help another team in need somehow and were never a real contributor so they can get a free year of grad school. This is how you make the transfer portal productive for the student athlete. Which is first.
That said, I think any kid should be able to transfer to any school at any time like any other 18-22 year old in college. The feudal kings will eventually die when they no longer can control those that make them.
Transfer portal = good