I missed this thread back in 2016, or at least the part about Fr. Fahnestock. I saw him in Watkins, CO in 2017, offering un-announced Masses at St. Isadore's several Sundays in a row while he was visiting his family there. So if it's true that he'd left the priesthood by 2016, he was back in cassock and offering Mass in 2017. He was not with the SSPX at that time, but apparently on friendly enough terms with them to offer Mass in their church.