I would take exception to this interpretation of his words regarding the authority of his statements.
1 Corinthians 7:10 KJV
And unto the married I command, yet not I, but the Lord, Let not the wife depart from her husband:
VS
1 Corinthians 7:12 KJV
But to the rest speak I, not the Lord: If any brother hath a wife that believeth not, and she be pleased to dwell with him, let him not put her away.
I do not believe this is a difference of inspiration. For then we have a passage of Scripture that is literally just one man's opinion, and therefore not authoritative. But the teachings of the apostle Paul are in fact authoritative, and he wrote what he wrote by divine inspiration.
So what is he saying here?
The the first instance involves a restatement of a direct instruction or teaching from the Lord, and the second instance involves a statement of apostolic teaching. Both are inspired, and both are authoritative, but one is directly from the Lord (either a paraphrase of the Law, or a teaching actually declared by Christ during His ministry) and the other is directly from the apostle (who, being led by the Spirit and authorised by Christ as an apostle has the authority to establish "ordinances" or rules which are binding upon the church).
The alternative, that Paul was declaring he was just giving his human, uninspired opinion, breaks the chain of Scripture in that we now have "scripture" that quite honestly should not be considered Scripture. What else in the Bible is not Scripture? What else is just Paul's opinion and therefore uninspired and therefore non-binding?
"οὐκ ἐγὼ, ἀλλʼ ὁ Κύριος] The negation is absolute. Paul knew from the living voice of tradition what commands Christ had given concerning divorce,
Matthew 5:31 f.,
Matthew 19:3-9;
Mark 10:2-12;
Luke 16:18. Hence ὁ Κύριος, sc[1104] παραγγέλλει, for the authority of Christ lives on in His commands (against Baur, who infers from the present, which is to be supplied here, that Paul means the will of Christ made known to him by inspiration). It is otherwise in
1 Thessalonians 4:15. As regards the ἐγώ, again, Paul was conscious (
1 Corinthians 7:40) that his individuality was under the influence of the Holy Spirit. He distinguishes, therefore, here and in
1 Corinthians 7:12;
1 Corinthians 7:25, not between his own and inspired commands, but between those which proceeded from his own (God-inspired) subjectivity and those which Christ Himself supplied by His objective word. " (Meyer's New Testament Commentary)
"The Lord Jesus, during his ministry on earth, delivered many precepts of his law in the hearing of his disciples. And those which he did not deliver in person, he promised to reveal to them by the Spirit, after his departure. Therefore there is a just foundation for distinguishing the commandments which the Lord delivered in person, from those which he revealed to the apostles by the Spirit, and which they made known to the world in their sermons and writings. This distinction is not only made by Paul; it is insinuated likewise by Peter and Jude,
2 Peter 3:3,
Jdg 1:17, where the commandments of the apostles of the Lord and Saviour are mentioned, not as inferior in authority to the commandments of the Lord, (for they were all as really his commandments as those which he delivered in person,) but as different in the manner of their communication. And the apostle’s intention here was not, as many have imagined, to tell us in what things he was inspired, and in what not; but to show us what commandments the Lord delivered personally in his own lifetime, and what the Spirit inspired the apostles to deliver after his departure. This Paul could do with certainty; because, although he was not of the number of those who accompanied our Lord during his ministry, all the particulars of his life and doctrine were made known to him by revelation, as may be collected from
1 Corinthians 11:23;
1 Corinthians 15:3;
1 Timothy 5:18; and from many allusions to the words and actions of Christ, found in the epistles which Paul wrote before any of the gospels were published; and from his mentioning one of Christ’s sayings, not recorded by any of the evangelists,
Acts 20:35. Further, that the apostle’s intention, in distinguishing the Lord’s commandments from those he calls his own, was not to show what things he spake by inspiration, and what not, is evident, from his adding certain circumstances, which prove that, in delivering his own commandments, or judgment, he was really inspired. Thus, when he asserted that a widow was at liberty to marry a second time, by adding, (
1 Corinthians 7:40,) she is happier if she so abide, after (that is, according to) my judgment; and I think, or, (as δοκω rather means,) I am certain that I also have the Spirit of God, he plainly asserted that he was inspired in giving that judgment or determination." (Benson's Commentary)