The manager of each campaign reserves the right to exclude someone from the campaign without any further explanation. You have to accept it and move on. Certainly, no one except their manager can give you an exact answer, but only a guess.
The manager actually owes the participant an explanation and that has to be in the terms of the campaign the participants agreed to when they applied to join. Not giving clear explanation or making up new rules after the work has been done is shady business and deserving of a red trust, a flag may be to excessive but is also not off the table.
I believe the campaign manager should be giving the opportunity to defend themselves and answer to the numerous questions being asked, without their side, I will not be giving them a negative rating yet.