Galatians 2 pushback: Peter's refusal to eat with Gentiles as social discrimination

The legitimate pushback: Galatians 2 describes social interaction (Peter refusing to eat with Gentiles), which seems to prove Westfall's point about social dynamics. Paul opposed Peter to his face because Peter withdrew from eating with Gentiles when the circumcision party arrived from Jerusalem. This looks like a social/relational issue, not just an abstract theological one.