The counter is that the troll argument compares a substantial community of good-faith actors (transgender people) to a largely imaginary community of bad-faith

The counter is that the troll argument compares a substantial community of good-faith actors (transgender people) to a largely imaginary community of bad-faith actors (people pretending to be trans-racial) and from that point on it assumes that those groups are entirely alike in every way, even though one of those groups doesn't exist to any meaningful extent.