There is no conflict of Paul’s and Jesus’ words. Evil must be addressed. Jesus also said to treat an unrepentant one as a Tax Collector and a Man of the Nations (Matt 18:15-19).
Ray Franz addresses this topic in detail in his book, ISOCF.
Yes there is a biblical DF, but the Jws misuse and abuse the provision. Paul’s words relate to a Christian who is a fornicator, Drunker, etc., not one who was this one time in the past. The Jws treat this as a state, not as an incident.