Purgation isn't to be regarded as a substitute for Judgement. It is what happens to many of the souls who are Judged, as part and parcel of their Judgement. As St Paul intimates, some of those who are Judged will be saved: yet their work will be burned up.
If anyone builds on this foundation with gold, silver, precious stones, wood, hay, or straw, the work of each will come to light, for the Day will disclose it. It will be revealed with fire, and the fire (itself) will test the quality of each one's work. If the work stands that someone built upon the foundation, that person will receive a wage. But if someone's work is burned up, that one will suffer loss; the person will be saved, but only as through fire.
That entire chapter is talking to and about the leadership of the church. And it referenced the people they were teaching who did or didn’t maintain the faith. Some fell away because of poor “milk” only teaching and some stayed true to the faith because of “meat” teaching so the leadership would get more rewards if they taught strong “meat” taught Christians. It has nothing to do with purgatory.