I don't think he could have waited without damaging his prospects. Today, the team he'll go to, is a combination of NIL money and opportunity. By opportunity I mean how committed the staff is to starting him, the QB room depth chart, and the talent of the team around him. Many teams are going to offer QBs and will pick off the best fit. so he's competing with the starter from OK, Duke, FSU, USC. Liberty, and tOSU to name a few. A lot of the best slots will be taken. A lot of QBs already committed (FSU, Utah, Duke, Houston).
In the end, college is about preparing and giving them the best opportunity to succeed. With Allar coming back and the staff being so impressed with Grunk, this is what had to happen.