I'd love to know the process for this, because I agree that Illinois changed their interest. Now, the staff already had Von Seggern and Thomann committed. They also were pushing in all their chips on Micah Smith. But during that December - March timeframe, there are no camps, games, etc. It can't be a situation where they saw more performance from Riordan and changed their tune. Maybe it was a NIL cost (seems unlikely). All of those details lead to me finding it funny that Illinois had him as their A target for interior o-line and then something change during the late winter time period.
Short version: It's interesting when teams completely shift their interest in the winter period, especially for prospects they are prioritizing but then decide they are no longer interested.