I had a suspicion this would be the case. RC teaching leaves the door open to the possibility that Paul wasn’t all, or even mostly, right when he challenged Peter’s shunning of gentile believers.
However did I manage to guess correctly? [And note that they somehow found a ‘Protestant’ to support their position—as if that makes it right. Smh.]
‘Its not even certain that Paul was totally right and Peter completely wrong. The prominent Protestant scholar James D. G. Dunn wrote about this question (Unity and Diversity in the New Testament, London: SCM Press, 2nd edition, 1990, 253-254), and pointed out that because we have only Pauls report, we cant finally decide who was right and wrong.
Dunn thinks the internal evidence of the passage provides clues suggesting that even Paul himself didnt think he was decisively correct, over against Peter:
[I]f Paul had won, and if Peter had acknowledged the force of his argument, Paul would surely have noted this, just as he had strengthened his earlier position by noting the approval of the pillar apostles in 2.7-10.
Dunn even goes so far as to assert: it is quite likely that Paul was defeated at Antioch, that the church as a whole at Antioch sided with Peter rather than with Paul (italics his own). If this is true, then obviously, the incident would provide no disproof for the papacy at all. Dunn notes that Paul also seemed to change his tune later on:
[I]t can hardly go unnoticed that Pauls advice to such communities in I Cor. 8,10.23 11.1, and Rom. 14.1 15.6 (not to mention his own practice according to Acts 21.20-26) is more in line with the policy of Peter and Barnabas at Antioch than in accord with his own strongly worded principle in Gal. 1.11-14!’
(I never heard of Dunn, btw, but from this excerpt he sounds like a lightweight.)
http://www.themichigancatholic.org/2016/04/pauls-rebuke-peter-prove-peter-wasnt-infallible/
Okay, I educated myself re the James Dunn who isn’t convinced Paul was altogether right in rebuking Peter. I am now able to offer a one word summary:
Liberal.
The longer version: Liberal as the day is long.