St. Peter was the chosen one of God to take the gospel to the Gentiles.
"And when there had been much disputing, Peter, rising up, said to them: Men, brethren, you know, that in former days God MADE CHOICE among us, that by MY mouth the Gentiles should hear the word of the gospel, and believe.
Did God change His mind? I think not. St. Peter was above St. Paul in authority in the Church and sent St. Paul out as a helper to spread this message.
"Go thy way, for he [Paul] is a chosen vessel unto me, to BEAR MY NAME BEFORE THE GENTILES, and Kings, and the children of Israel".
What makes him MORE chosen than St. Peter or any of the other Apostles that spread and bore His name before Gentiles and the children of Israel?
"St. Peter was the chosen one of God to take the gospel to the Gentiles."
------ Nope. Even Peter would have disagreed with you, because he recognized all of Paul's Epistles to all of those Gentiles as Scripture, particularly Galatians 2:9 where we read: "When James, Cephas, and John ... perceived the grace that was given to me, they gave me and Barnabas the right hands of fellowship that WE SHOULD GO TO THE GENTILES, and they unto the circumcision".
Peter went to the Jews and Paul to the Gentiles and Rome.