If your customers wish to exclude adult content from their search results and you feel it necessary to address that wish, you provide them with a little check box on the search page that says "exclude adult content from results". You do NOT start stripping authors of their sales rankings and censoring for everyone based on a very skewed definition of 'adult' which seems mainly to rely on the content touching on GBLT themes whether explicit or not so that they do not appear in all department searches thereby hurting the publishers and authors who provide the content on which your business depends. Discrimination and censorship in one go from a bookseller = FAIL.
Methinks the only thing that probably stopped you including hetero romance and erotica in this (though some authors seem to have been caught anyway) is the fact that romance is the single biggest selling genre in most of the world and you just can't be that dumb. Though you've probably managed to severely annoy a large percentage of the romance writer and reader population with this.
No dollars from me until you fix this.
If people want some alternative bookstore suggestions (particularly if you're in Oz):
www.bookdepository.uk (free shipping everywhere unlike Amazon)
www.fishpond.com.au (free shipping for orders over $50 au)
www.deepdiscount.com (again, cheaper international shipping than Amazon)
www.powells.com (again, cheaper international shipping than Amazon)
Finally Amazon Rank.