In deciding who “won” the debate, one has to keep firmly in mind that the debate wasn’t about purgatory, but rather it was about whether purgatory was what Paul was talking about in I Cor 3. It’s purely an exercise in exegesis, not theology.
Paul is referring to himself and fellow ministers as builders and the believers who make up the church (to whom he writes the Epistle) as the building. So if this passage is about purgatory it is only in reference to ministers.
Note that Paul says that Christ is the foundation and that the various ministers (He, Apollos and others) are building the church upon that foundation. He then goes on to state that the materials can be precious or not-that fire will determine their quality.
Thus Paul is saying that each minister will have an impact on the quality of the people in the church. One sees the same idea in the initial Chapters of Revelation, where the “angels” ( Gk ‘sent one’) or the ministers of those churches are told that the quality of their work has an impact on how their church members will be judged.
It would seem that Paul is referring to the fire of judgement, possibly through tribulation, through sickness and dissension in the body-all of these being mentioned in I Cor as punishments on the church for its sins.
It is also important to keep in mind that Paul starts I Cor by pointing out that Christ’s body is divided by those who put their loyalty to their favourite teacher ahead of their loyalty to other believers who don’t give their loyalty to the same teacher (funny how we never hear this passage with Peter’s name in it brought up by Catholics

) . In continuing this thought in chapters 2 and 3 Paul is pointing out that if a minister’s efforts have only produced church members who are contentious and prone to disunity that there will be judgment and that the teacher will suffer loss (have nothing to show for his ministry)-as anyone does whose building burns down-but will still be saved.
It seems clear that Paul is saying that he, Apollos, Cephas
et al. will be saved if the Corinthians continue on in sin and disunity. This will lead to continued and eventually eternal judgment for the church members on “the Day”. Paul and the other ministers will have to stand before God without these believers and lose the “wage” they would have gotten as successful ministers and shepherds while still holding on to their individual salvation. In the hope of presenting the Corinthians to God as gold, silver and precious gems, Paul has written this corrective Epistle.
Here is the passage in full:
1 And I, brethren, could not speak to you as to spiritual men, but as to men of flesh, as to infants in Christ.
2 I gave you milk to drink, not solid food; for you were not yet able to receive it. Indeed, even now you are not yet able,
3 for you are still fleshly. For since there is jealousy and strife among you, are you not fleshly, and are you not walking like mere men?
4 For when one says, “I am of Paul,” and another, “I am of Apollos,” are you not mere men?
5 What then is Apollos? And what is Paul? Servants through whom you believed, even as the Lord gave opportunity to each one.
6 I planted, Apollos watered, but God was causing the growth.
7 So then neither the one who plants nor the one who waters is anything, but God who causes the growth.
8 Now he who plants and he who waters are one; but each will receive his own reward according to his own labor.
9 For we are God’s fellow workers; you are God’s field, God’s building.
10 According to the grace of God which was given to me, like a wise master builder I laid a foundation, and another is building on it. But each man must be careful how he builds on it.
11 For no man can lay a foundation other than the one which is laid, which is Jesus Christ.
12 Now if any man builds on the foundation with gold, silver, precious stones, wood, hay, straw,
13 each man’s work will become evident; for the day will show it because it is to be revealed with fire, and the fire itself will test the quality of each man’s work.
14 If any man’s work which he has built on it remains, he will receive a reward.
15 If any man’s work is burned up, he will suffer loss; but he himself will be saved, yet so as through fire.
16 Do you not know that you are a temple of God and that the Spirit of God dwells in you?
17 If any man destroys the temple of God, God will destroy him, for the temple of God is holy, and that is what you are.
Though I don’t totally agree with your interpretation, if I give you the “us/them” segregation between Paul and ministers and the laity in vv9-10, it appears he moves out of that distinction in vv11-17.
Given that Paul an Apostle calls himself a “builder” and Apollo a “waterer”, if I follow your understanding, Paul would then be limiting the verses in question to just Apostles.