Clearly Airbnb doesn’t care. They only sided with the guest after a big newspaper got involved, then gave the host no punishment, not even a slap on the wrist (a warning that next time something could happen is toothless).
It's worrying. Assuming there's a risk of such fraud going undetected and harming a paying guest, I think a punishment more serious than a warning could easily be justified. Even if it isn't reasonable to prosecute, banning the host would help. Users of other online services are sometimes banned without warning or explanation, so the deference to Airbnb hosts is jarring.