The ASA and ads for offensive products

The UK’s Advertising Standards Authority would seem to have a particular remit: advertising.  A recent adjudication, however, suggests that the ASA will go beyond that, at least online.  Zazzle Inc, No. A13-247896, involved a complaint that Zazzle’s offering of a mug with the words “World’s Greatest Dad” and an image of notorious child rapist/abuser Josef Fritzl was offensive.  There doesn’t appear to have been any advertising other than the image of the mug itself on the seller’s webpage.  Zazzle didn’t respond to the ASA’s inquiry.  The ruling stated:

We noted the product was navigated to via the humour section of the personalised product website, but noted the product was not otherwise targeted. We considered that the juxtaposition of the image of Josef Fritzl next to the words “World’s Greatest Dad” made light of the widely reported incidents of sexual and physical abuse of his daughter and therefore concluded that the ad was likely to cause serious and widespread offence.

Of course, it’s not the ad but the product that’s offensive.  So how far does the ASA’s authority over expressive products extend?