Yes, this whole thing could have been handled better by Jon, by BJM, by Richie.
No, Richie doesn't have to tell us what the private matter is. I wouldn't even see the point of his telling the reason...just so we could sit in judgement for another 200 pages as to whether it was a worthwhile reason for him to take off from the tour and causing a nightmare for his bandmates and the fans?
I trust Richie enough to know that it is not frivolous.