Most Christians do not believe that the Apostle Paul recommended treating enemies of the Christian congregation as if they are literally dead when they are very much alive. In 1 Cor. 5:11, Paul merely recommended that Christians not associate with fornicators, idolaters, drunkards, extortioners, etc. Paul did not mention anything about not talking with people when we meet them in a public place.
Also are all disfellowshipped Jehovah's Witnesses evil and wicked? No they are not. Many just disagree with Watchtower interpretations of the Bible. See What The Bible Says About Disfellowshipping
What if you believe that the Apostle Paul did recommend disfellowshipping and shunning in 1 Cor. 5:11? Certainly your interpretation is a valid one and based on the Bible. The question you should ask yourself is this. Did Jesus say anything in the Bible about Apostate Jehovah's Witnesses and enemies? Yes he did. Jesus told his followers to love their enemies. Luke 6:35-37, Mathew 5:44.
Jesus warned his followers against the leaven of the Pharisees. The Apostle Paul converted to Christianity after Jesus died. Before that he was a zealous persecutor of Christians. He was even responsible for the death of some Christians. In addition, Paul claimed to be a Pharisee after converting to Christianity. Acts 23:6 See Facts About The Apostle Paul