I'm pretty sure that animated sex that includes penetration is not abusive, whereas a porn video of actual people is unsuitable material for the Portal. That's the main distinction here, in any case. Plus, the rating is somewhat appropriate - I would've given it a "Mature" rating rather than "Adult" but that's just my two cents.
As for being stolen, I'm not so easily convinced since the NG'ers profile is rather substantial compared to the obvious accounts that were made within days of submitting stolen flashes. Maybe you should PM the submitter about it and see what he has to say. After all, it is the submitter's responsibility to let the audience know that the flash exists on other sites and that they are the author of those works as well to avoid being falsely flagged.
Otherwise, you can go straight to PM'ing Tom or Wade about the stolen submission being passed.
if you'd like more guidance on dealing with these situations, PM me and I'll help ya out.