You are trying to equate purgatory with the believer’s judgment - not the White Throne Judgment, but the individual believer’s judgment where there are rewards, and there are losses, for what was done in the body. That isn’t purgatory.
The passage through purgatory occurs after the Particular Judgement - that of the individual believer if he had been judged saved for eternal life. If the passage through purgatory is not necessary as the believer was sanctified already, then that can be called a reward, indeed, by analogy with how St. Paul says those who go through purgatory "suffer loss". The purgatory is not however itself a "judgment" and it would not occur to me to "equate" the two.