Catholics believe that the Church is the mystical Body of Christ, visible upon earth. As such, the Church, having the mind of Christ, is most intimately related to the Word of God and cannot err in the dogmatic expression of her understanding of the Word.
Of course, this is deeply problematic on at least two grounds:
1. If the church has the infallible mind of Christ, then what constitutes the church? Does this extend to every Christian individually? To each Christian in concert with every other Christian? Or to a subset of Christians?
As a Catholic, he obviously has to par this down. But his allusion to 1 Cor 2:16 has no such restriction.
2. If "the Church" has the mind of Christ, then why would would ecclesial infallibility be limited to "dogmatic" expressions? Was dominical infallibility limited to "dogmatic" expression?