[Esaias]

Originally Posted by votivesoul

I disagree.

The commentaries you cite bring up 1 Corinthians 7:40.

The key terms there are: γνώμην gnomen and δοκῶ doko.

The first refers to a personal opinion or judgment, i.e. advice (See 2 Corinthians 8:10, vis a vis verse 8, where Paul differentiates his advice from a commandment).

See: https://biblehub.com/greek/1106.htm

The second means "to suppose", i.e. what seems to be according to one's own subjectivity.

The term is used similarly of the Gentiles, who think, i.e. suppose that their "much speaking" per the KJV, results in their gods hearing them (Matthew 6:7) or when the disciples thought they had seen a ghost/spirit on the waters, but it was actually the Lord (Mark 6:49), or when the disciples argued over who should be deemed greatest in the Kingdom of God (Luke 22:24).

See: https://biblehub.com/greek/1380.htm

In each case, there is always subjectivity and opinion.

As for why Paul would give us an opinion not fully binding on the church, here is my take:

Keep in mind in 1 Corinthians 7, he is dealing with marriage, and he was very careful to not abrogate what he would later write in the letter (and elsewhere): that the head of every wife is the husband. He wanted to be very careful about interfering with another man's headship over his own wife. So, he very carefully distinguished between what he knew was clear in the Law, and what Christ had taught, and what he thought was best if or whenever a situation in the church arose regarding marriage that wasn't covered by the Law or in the teachings of Christ.

Paul's personal opinions, as recorded in Scripture, giving direction to the church, are inspired by God, and are the voice of God speaking to His sheep. After giving his opinion, he states "and I think I also have the Holy Ghost", meaning his opinion is, in his estimation, inspired by God.

Cambridge Bible commentary notes:
and I think also that I have the Spirit of God] Not that there was any doubt in the Apostle’s mind on this point. The word used implies full persuasion that in the advice he had given he was speaking under the direction of the Holy Spirit.

Bengel:
1 Corinthians 7:40. Μακαριωτέρα, happier) 1 Corinthians 7:1; 1 Corinthians 7:28; 1 Corinthians 7:34-35; Luke 23:29.—δοκῶ, I think) The Corinthians thought more of themselves than was right, and less of Paul. Paul with delicate pleasantry, ἀστέιως, gives them back their own expression.—κᾀγὼ) I also, no less certainly, than any of you [who may think he has the Spirit].—Πνεῦμα Θεοῦ, the Spirit of GOD) whose counsels are spiritual, divine.

Barnes':
And I think also that I have the Spirit of God - Macknight and others suppose that this phrase implies entire certainty; and that Paul means to affirm that in this he was clear that he was under the influence of inspiration. He appeals for the use of the term (δωκῶ dōkō) to Mark 10:32; Luke 8:18; 1 Corinthians 4:9; 1 Corinthians 8:2; 1 Corinthians 11:16; Hebrews 4:1, etc. But the word does not usually express absolute certainty. It implies a doubt; though there may be a strong persuasion or conviction; or the best judgment which the mind can form in the case; see Matthew 6:7; Matthew 26:53; Mark 6:49; Luke 8:18; Luke 10:36; Luke 12:51; Luke 13:24; Luke 22:24; Acts 17:18; Acts 25:27; 1 Corinthians 16:12, 1 Corinthians 16:22, etc. It implies here a belief that Paul was under the influence of the infallible Spirit, and that his advice was such as accorded with the will of God. Perhaps he alludes to the fact that the teachers at Corinth deemed themselves to be under the influence of inspiration, and Paul said that he judged also of himself that he was divinely guided and directed in what he said - "Calvin." And as Paul in this could not be mistaken; as his impression that he was under the influence of that Spirit was, in fact, a claim to divine inspiration, so this advice should be regarded as of divine authority, and as binding on all. This interpretation is further demanded by the circumstances of the case. It was necessary that he should assert divine authority to counteract the teaching of the false instructors in Corinth; and that he should interpose that authority in prescribing rules for the government of the church there in view of the special temptations to which they were exposed.

JFB:
I think also—"I also think"; just as you Corinthians and your teachers think much of your opinions, so I also give my opinion by inspiration; so in 1Co 7:25, "my judgment" or opinion. Think does not imply doubt, but often a matter of well-grounded assurance (Joh 5:39).