All existing pandas are owned by the PRC so the chance of somebody selling a panda for real, vs selling some sort of panda themed toy/book/etc, is virtually nil. No human would make this mistake; their filter is braindead.
That's not to defend Facebook's approach to ad management whatsoever. I definitely agree that it is far too blunt a tool for the problem.
Pretending the problem doesn't exist, however, because one example is unlikely is just intellectually dishonest.