As I understand, the May 1st date was for a 1st school transfer providing immediate eligibility WITHOUT a release from your previous school. After May 1, an athlete needs a release or an appeal to be approved from the NCAA to avoid a redshirt. I'm guessing, but have no proof that W never gave him a release.
People mentioned scholarships. I don't know how those enter into things but IIRC, an athlete not on scholarship doesn't need a release. Since teams get 9.9 scholarships, effectively one per weight I'd assume W had to give Lamont a full ride to get him to sign, unless they get NIL money instead. Kyle could not have had much scholarship $ assigned to him for the upcoming season.