Yes, I believe you are.
I pointed out that, according to a strict application of your principle...namely, that when specific people are given specific commands by the Lord, they are to obey them explicitly, neither adding nor omitting anything...Christians in general should not presume to follow orders that were clearly addressed specifically to the churches in Ephesus and Colosse. According to that principle, those orders aren't for us...they are only for Ephesians and Colossians.
But that's a fallacy, one you spotted immediately. The modern church operates under the understanding that principles that apply to those historical churches apply to modern churches as well.
Understand, please, that this "understanding" that I cite above is not stated explicitly in scripture, all of which was written for a specific place and time that is neither here nor now. We appropriate the scriptures and apply them to our lives, and to the local bodies in which we worship.
What does that mean in terms of practice? It means that some interpretation must be made, some reasonable adjustment to our practice which allows for differences between Asia Minor and here, and between 100 AD and now. For example: I bet you worship in a church building. The first-century church worshiped in homes, or in synagogues. Why should we feel free to worship in a building with no first-century precedent, and yet not feel free to worship with instruments that have no first-century precedent? Particularly when Israel's great hero David was a harpist and psalmist of the first degree?
I ask you to understand what you know, and how you know it. No analysis of the original Greek texts for Colossians or Ephesians can squeeze the meaning "without instruments" from the relevant passages that deal with singing hymns of praise.
We don't need a biblical citation to know that we should wear clothes to worship, because going clothed in public is the usual practice. Likewise, for many people, accompanying singing...even worship singing...with instruments is the usual practice. This is the understanding under which we operate.