The 105 fall camp roster and the 85 scholarship limit are two different things. Bo can add a player to the 105 roster at anytime, and yes he was saving a spot for Bubba. So, he can add someone to the camp for the rest of the week, or just wait until next week when school starts.
As far as the scholarship that Bubba had, that can be given to a walk-on who is a senior this year, and then it will be free to be used for next year. Who knows what Bo and the rest of the football admin staff will do with that scholly for this year. Also, just because Middleton and Okafor are not on the 105 for camp, it doesn't mean it frees up a scholly, unless those guys are kicked off/asked to leave the team after the season.