But that is the point, Apple have not lost the information - they still have their icon and can keep using it. There's a distinction between that and someone breaking into Apple's computer system and erasing all of their other copies of the icon, which would be the closest analogy to classical theft in this case.
I appreciate the appeal to what feels like common sense, but right now more than ever, the distinction between "classical theft" and replicating a series of ones and zeroes is extremely important. A war of minds is going on, and the relegation of all things copyright into the category of "theft" attempts to subtly justify any reaction to copyright infringement by making it equivalent to deprivation of property.
This is a tough topic because the word steal does have a valid semantic meaning in this context, and anyone who argues with common use of language always comes off as pedantic ('what is an iTouch? It's an iPod Touch!!!'), but its important for those of us who understand how digital media works continue to continue emphasizing the real world differences between theft and copyright infringement.
It's not theft of the digital entity, it's theft of the time and effort that went into creating the digital entity. The relevant concept is Theft Of Services.
Theft of services still implies the consumption of someone else's resources. By not paying for the service, the provider faces tangible losses (because the opportunity to service a paying customer is lost). In this particular case, Apple loses absolutely nothing. The designer is still wrong (and IMO, plagiarizing copyrighted design assets merits termination), but Apple's capacity to service their customers is not hindered by this.
