Good additional points Metatron.
When you examine the Greek words the apostle Paul used, it is apparent he meant to avoid only intimate, close, social contact with persons removed from the congregation. Polite, courteous social communication was fine, such as JW's treat the average worldy person. There were very different NT Greek words for both, and Paul only used the former when discussing treatment of disorderly and expelled persons. This is why he said in 1 Cor 5 not to eat with them, which denotes close, intimate, social settings. And it explains why in Thessalonians Paul exhorts not to shun them but to admonish them, meaning you can still communicate with them but at arms length, as it were.
The Watchtower's flawed interpretations and application of scripture on this matter are embarrasingly easy to see with a little research and common-sense.
Basically, they adopt a twisted, pharasaical position on this because it is self-serving, being such a powerful fear-control weapon to keep the flock in morbid submission. To their disgrace, it is a far cry from the balanced and sensible approach taught by Paul in harmony with the law of love.