This is fall camp, not UConn game prep. If they were going to just be suspended for UConn, it wouldn't stop them from practicing with the 1s. It could be discipline, that they have to earn back the right to start. Or it could just be that starters from the end of the season are currently first team and the players that were injured or are new have to earn the starting position during camp. Last, it could even be he wants to see certain match ups or give the QB/WRs a chance to get timing down before throwing them against the better defenders.
Again, it is the first day. Getting first team reps won't mean much until closer to the end of fall camp.