Didn't cyclops come to an 'understanding' with cap in a+x? And dark beast was the one sending the sentinels after him?
They weren't trying to scapegoat mags, they were trying to make him 'happy'. The other heroes jumped to the conclusion that it was mags fault because he the one whose usually the megolmanic in the family (but they also said they were going kill his 'whole family, so clearly no plan to throw the blame to mags and get off Scott free)