Had Peter lost his place of primary authority among the apostles?
Yes. Peter had already lost his place of primary authority and was not even moderating the meeting. James, who was not one of the twelve, was at the head of the list. Paul is described as the primary apostle now, while Peter, James, and John only seemed to be pillars.
Les explains that Peter had already lost his place of primary authority and was not even moderating the meeting; James was at the head of the list, though the context notes he was not even an apostle. The men who seemed to be pillars—James, Peter, and John—perceived the grace given to Paul, who was to be the primary apostle now. They gave Paul and Barnabas the right hands of fellowship, agreeing that Paul and Barnabas should go to the heathen (Gentiles) while they went to the Jew (the circumcision). Peter, James, and John would hold forth among the children of Israel for a few more years, but it was practically a lost cause because of Israel's unbelief. That is why Paul had to constantly defend his apostleship.