I disagree with Aloarjr810 and spmcgivern on this one.
I don't see what your disagreeing with here
Yes that is the rule(s) in the USBC Rulebook, but the league can supercede those rules with ones of it's own. If their rules state you must belong to this organization in order to be a member in good standing
Yes a league rule can supercede USBC rule (Though not all)
As for having rule that you have to belong to certain organization.
Sure they can do that, it's called a "closed league", But the quoted rules above have nothing to do with that.
The rules quoted are dealing with the time limit on filing a protest.
and it doesn't state there is a time limit on when this can be enforced then they can go back over the entire season and forfeit games of teams with illegal bowlers.
No, If the league rules don't state or address time limits on protests, then the USBC rules would apply.
So given the the way the usbc rules read, it is unlikely they can go back and make the teams forfeit games back to the beginning of the season.
It would all depend on what the league rule specifically states.
Yes, it would all depend on just what is wrote in the league rules.
(Though I find it unlikely the league addressed time limits on protests in the rules, a lot of leagues never think about it.)