If they're shunning normal people, at least that would be more consistent. Not saying it's right, but at least it makes more sense to their logic.
Theoretically, they're supposed to avoid people who could potentially subvert their faith. So it seems that wouldn't apply only to JWs who did something wrong.
I always thought it was kind of a double standard. As a JW, I would have to avoid some guy from the hall who might have been caught smoking, yet I was perfectly free to talk with anybody I work with who smoked. And insert the sin of your choice for smoking.
There were people at work living with their girlfriend/boyfriend, people who were having affairs, sex outside of marriage, doing drugs, gambling, etc. And I don't remember any particular strong warning about them. I certainly wouldn't be hauled in front of the elders if somebody saw me talking to them.