So consider that there are some Orthodox priests who are currently unable to offer public Liturgies. Some of them are in UAOC, some are in other groups, and some are free-lance, perhaps they started up their own chapel. Let’s say all of these priests might potentially receive faculties to offer public Liturgy, but so far, none have.
It doesn’t matter much whether they are, at the moment, in UAOC or other. All are under an Ordinary who they currently disregard. It is the “irregularity” of the priest, not this or that organization he happens to belong to today, which makes it imprudent for an Orthodox to attend his Liturgy, if he chooses to defy his Ordinary on this.
With Catholic churches it is a different situation.