Silly premise as it is well known that it is in very specific cases of mebaid atzmo lodaas that yo would say they have no chelek in olam habah. Most cases are when someone suffers mental illness. Perhaps you think we should ostracize the family members of someone suffering mental illness? That would be typically hypocritical of you.
Another flaw in your argument is that the reason why people distance themselves in all your examples is because of how they or their children may be affected by the actions of the “evildoer” which clearly does not apply here. (don’t throw in emotions here that is not a valid reason).