This a question which will likely never be answered. We probably need to get comfortable with that. I want to think Walton is a smarter than average football player who kept his nose down and graduated from a top university with middling grades. GT is very picky about their admissions to the MBA program and Walton likely realized his chances of making an NFL roster are pretty slim. Getting his MBA on a free ride and getting too play football is not a bad deal. And, Ole Miss with Kiffin at the helm is a good choice.
Looking at it from Kiffin's POV is similar. He has a need on his defense and is looking at the portal to fill that need. Walton is there and might be a starter for one year. I cannot see Ole Miss throwing a ton of money at him. They know he could have stayed at GT if there was a place for him in school, so he is leaving to go somewhere. That they were able scoop him up at the last minute probably means they failed to lure someone they preferred.
But, the bottom line for me is that I don't want to view Walton through a negative lens. He seems like a good, hard working young man with his sights set on his post collegiate life. It seems out of character for him to collude with Kiffin to break the NCAA rules.