Well I've discovered who this ex-diocesan priest is. He is Fr Robert Morey from South Carolina. If his name sounds familiar, it's because he was the South Carolina priest that announced that he had refused communion to Joe Biden about four years ago when he stopped in South Carolina on the campaign trail. From my understanding of talking to some of the parishioners, he's semi-retired and I think is fed up with his bishop. He was offering the TLM at his diocesan church. I asked if Fr Morey was going to join the SSPX, and it seems that he's going to be more of a "friend of the Society" (probably like Bp Huonder is doing now). I don't remember if a reason was given for his unannounced visit to offer confessions. Maybe it's for pastoral reasons given the huge influx of indult refugees that have been attending the chapel this year.
While I have a lot of respect for this Novus Ordo priest for acting Catholic by publicly refusing Joe Biden communion, I would not approach this priest for any of the sacraments. Nothing personal against him, but since he was ordained in the new rite by a new rite bishop, I have doubts about his validity. It would be great if he would get conditionally ordained, but the neo-SSPX doesn't do that anymore. Hopefully he's only doing confessions as an extra option and isn't doing something like consecrating hosts for the chapel...