Don Johnson

Paul is my hero, but he does say he is the least among the apostles, which includes all the others named in Scripture at the time he wrote it.

But I have a big concern with your understanding.  It is that ALL apostles made a blunder.  I can see single ones making a mistake, like Peter and maybe Barnabas, but ALL?  How would we ever have confidence in what they later did?

Furthermore, my understanding of

Mat 18:18

Truly, I say to you, whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.

is that Jesus is using Jewish rabbinic terms to say the disciples can permit or forbid (that is, decide Halachah) and God will back them up in their decision (as well as guide them).

In other words, they ALL decided on something, so God has promised that they can do this.