Maybe we should direct JW's to read this Question Box revelation:
w06
2/15 p. 31 - "Finally, Jesus explained that if a person addresses
another, “You despicable fool!” he would be liable to the fiery
Gehenna. What, then, did the
expression “despicable fool” signify? It designates
a person as morally worthless, an apostate and a
rebel against God. So the person addressing his fellow as a
“despicable fool” is as much as saying that his brother should
receive a punishment fit for a rebel against God, everlasting
destruction. From God’s standpoint, the one uttering
such a condemnation against another could merit that severe
sentence—everlasting destruction—himself."
If a JW falsely slanders someone of being an apostate, they're condemning themselves.
Apostasy and heresy are not the same - the cult should educate themselves.