I don't think there is a conflict with the passage you referenced as it is talking about something else. 2 Peter 1:20 is not speaking about the interpretation of scripture, it is strictly speaking about prophesy - the foretelling of future events. Put in the context of verses 21 and 23, this passage is simply saying that prophetical passages in the Bible came not from the minds of men but as the direct words from God were put into the mouths of the prophets.
In short, per the Church, you are mis-interpreting the Scripture you posted. There is of course, a better explanation, and I wil post it when I find it.
*This shows plainly that the Scriptures are not to be expounded by anyone’s private judgement or private spirit; because every part of the Holy Scriptures were written by men inspired by the Holy Ghost, and declared as such by the Church; therefore they are not to be interpreted but by the Spirit of God, which He hath left, and promised to remain with His Church to guide Her in all truth to the end of the world. Some may tell us that many of our divines interpret the Scriptures. They may do so: but they do it always with a submission to the judgement of the Church and not otherwise.