I would like to know how you think you know that responsible Muslims don’t quietly inform the police if they have information on anyone? For sure they won’t run to the media or otherwise draw attention to themselves because they have the safety of themselves and their family to consider.
I think there are too many assumptions made that just because the decent Muslim communities don’t demonstrate or make public condemnations they somehow accept the grooming. I don’t think it’s true. I think they are reticent to openly condemn but may well be quietly helping where they can. Just as criminals won’t openly grass on one another, for their own safety, but do so quietly when crimes against kids are involved, this is probably no different.
Otherwise where are the police getting any information?