I don't know about A_ppl_e -- but there are loads of "reputable" companies that are constantly dueling in court about stolen intellectual property, proprietary code that gets "misused", and for that matter complete designs for medical and electronic devices. There is an entire industry around cracking through and reverse engineering this kind of stuff, including employed "actors" who gain access to things like the "reference document" you mentioned to make their jobs easier.
In fact, the super company you mentioned has done this before and recently, here's a link:
http://blogs.computerworld.com/16683/apple_steals_iphone_app_ideas_and_patents_them_and_lightsabers
While doing what your customer has asked you might not be the best option to provide a "warm fuzzy" feeling -- there are other options. There are different kinds of encryption tools, defining an IP or copyright before sending it for deployment as an app, or patenting the specific idea that your customer has.
They all have their different costs. -shrug- But even having these "blankets of protection" won't prevent all of the infringements your customer is afraid of -- there are ways around everything, if your product/idea is worth enough capital.
Good luck with your revisions or whatever other solution you come up with.
--tiff