This puts them outside the pale of Christian orthodoxy, and unless you're "inside" the pale you can be neither Protestant nor Catholic.
2 Timothy 3:16 All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:
Every word in the Bible is true, but there are no words that state that Peter was ever in Rome.
The Second Epistle of Paul to Timothy is written by Paul from Rome - most likely just prior to his death at the hands of Nero. At the close of this letter, in Chapter 4, Paul speaks of those that left him, and those that are with him ("...only Luke is with me."). Nary a word about Peter. I infer that Peter was not in Rome at this time - and if Peter was ministering to the Jewish-Christian community in Babylon, that would fit the greeting found in the 2nd Letter of Peter.
Now its certainly possible that Peter went to Rome after Paul's death -- but scriptures are silent on that point.
The net of all this? It doesn't matter to me whether or not Peter ever made it to Rome. He was an Apostle of the Lord and we are blessed to be built upon the foundation that they provided, purchased by the blood of Christ, and made alive by the Spirit
Ephesians 2:19-22 Now therefore ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household of God; And are built upon the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone; In whom all the building fitly framed together groweth unto an holy temple in the Lord: In whom ye also are builded together for an habitation of God through the Spirit.