Before anything else, I am not defending or aligning myself with the actions of this bishop. I am merely stating a theory about where this bishop is thinking he is getting the authority to do as he did.
The difference between SSPX and this priest lies in jurisdiction.
From how I understand it this particular priest is under jurisdiction of this particular bishop. Therefore this bishop thinks this priest is his subject, thus he thinks he has authority. Thus he acted as such.
In the case of SSPX, the jurisdiction they receive comes directly from the people who have asked them to come and provide them with the sacraments, the Church provides jurisdiction in the case of necessity.
Fr. Marrone cannot request a leave of absence, IOW ask permission, from someone who he will later on say has no authority over him, there is a conflict of thought there.
He either recognizes their authority over him or not and acts accordingly.