Of course he is. That is, he is giving us the true meaning of the text (aka interpreting it for us) That is the plain, common sense reading of the scripture at hand. I can see you prefer the KJV so, to quote again:
Simeon hath declared how God at the first did visit the Gentiles, to take out of them a people for his name.
He is saying here, OK guys, Peter has told you about how God is doing good things with the Gentiles. taking out "a people for his name" (interesting choice of words. that was reserved for Israel in the OT)
15And to this agree the words of the prophets; as it is written,
And so, James says, THIS IS IN FULFILLMENT OF THE PROPHECY (DING DING DING!!!!) which I am about to quote.
16After this I will return, and will build again the tabernacle of David, which is fallen down; and I will build again the ruins thereof, and I will set it up:17That the residue of men might seek after the Lord, and all the Gentiles, upon whom my name is called, saith the Lord, who doeth all these things.
A couple of observations: 1) Literally, the Hebrew does not say "after this" but "in that day" referring to the day of the restoration of Israel (check it out, Amos 9), and its consequent dominion over Edom and all the heathen. 2) James clearly states that THIS PROPHECY IS BEING FULFILLED NOW, not that this prophecy will be fulfilled later. That would be silly (more on that below). This is clear because it is the whole issue of the GENTILES that is at stake, and James is saying "LOOK GUYS, DON'T YOU SEE? THIS IS THE DEAL GOD TALKED ABOUT ALL THRU THE SCRIPTURES. HE SAID THAT THE HOUSE OF ISRAEL WOULD BE EXPANDED AND RULE OVER THE GENTILES!! THIS IS IT! THEY ARE COMING TO THE TRUE FAITH, EVEN NOW!!. GOD SAID IN PICTORIAL LANGUAGE THAT THE RULING HOUSE OF DAVID WOULD BE RESTORED TO PRIMACY AND THE GENTILES WOULD BE RULED OVER BY THAT HOUSE! WE HAVE DAVID'S GREATER SON RULING AND HE IS BRINGING THE GENTILES IN SUBMISSION TO HIM!!!!"
The view you are putting forth really makes no sense at all in its context. It is like Peter says "IT IS BY FAITH FOR THEM AND US" and Paul and Barnabas stand up and say "YEAH!! AND GOD IS DEMONSTRATING HIS POWER AND GOODNESS BY CHANGING LIVES AND PERFORMING GREAT SIGNS!!" Then imagine James standing up and saying "YAY! AND YOU KNOW WHAT, GUYS, SOME DAY GOID IS GOING TO REBUILD THE TEMPLE/CITY OF JERUSALEM/DAVIDS' HOUSE (or whatever that "literal" thing was.... i think you called it the city of Jerusalem. hmmmmmmmm). I can see the whole assembly going quiet and saying "what in tarnation does that have to do with what we were talking about?" It just doesn't follow, it is out of context, and doesn't fit into the discussion at all.
The ONLY reason one would adopt such a reading would be an unbiblical predetermination not to allow 'allegorization" even if the Holy Spirit spoke it through the mouth of James. And He did.
At the Jerusalem Council, the Apostle James quoted verses 11 and 12 to support his view that the Gentiles of his day did not need to submit to circumcision and the Mosaic Law to obtain salvation or to live as Christians (Acts 15:13–21). He knew that the judgments of Israel were not yet over (cf. Matt. 24:1–22; Luke 21:5–24; Acts 1:6–7). He also knew, from this passage and others (Isa. 42:6; 60:3; Mal. 1:11), that when God restored the house of David Gentiles would have a share in that rule as Gentiles. James concluded, therefore, that Gentiles did not need to become Jews to enter into these (millennial) blessings. He did not mean that the church fulfills the promises to Israel but that since Gentiles will experience millennial blessings as Gentiles they do not need to become Jews in the church.
Tom Constable. (2003; 2003). Tom Constable’s Expository Notes on the Bible (Am 9:12). Galaxie Software.