As far as the biblical account, I think people really should be looking at the exegesis of all Christian scripture, not just what is in the Bible.
The Bible as most people know it is a filtered version fitted to a particular branch of Christianity. Like the WTBTS has its own ‘translation’ that adds and removes certain components based on their own interpretation, the King James has the same ‘problem’.
Beyond that, Peter denied Christ and was still forgiven, the Pauline letters recount a single incident which does not match general consensus in ANY other scripture. Jewish scripture even pre-Christianity (eg. Sirach which was ~150BC), already mentions forgiveness needs to be given BEFORE prayer can be accepted, which is also what Jesus said (leave your offering at the altar and go make peace or if you do not forgive, neither can the father) and both Pauline and others reflect the same sentiment.
Hence 1 Cor cannot refer to excommunication or shunning from a church (the cutting off of salvation as the WTBTS teaches) because by doing so, the church would put itself as a mouthpiece of God, because only God can make a perfect judgment and only God can perfectly forgive. It talks about discipline, and still accepting that person as a brother (2 Thess 3:15). So if you need ‘the church’ to excommunicate (withdraw salvation) and ‘the church’ to reinstate (restore salvation or provide forgiveness), you are elevating the people in the church to be channeling the divine, which would imply, based on the exegesis of scripture, this is akin to spiritism in the WTBTS elder bodies.