Windows 7 x64 is not pure 64-bit because it contains a 32-bit compatibility layer (as King Arthur pointed out earlier), so that 32-bit applications can be executed. Is that a fault? No. It's a feature.
Windows comes with a wide range of features, some of which are innately tied into the operating system. For example, the Explorer program. There's a component of it that is used for Internet browsing, and one for browsing local files and folders. You CANNOT remove it from the system. No matter how badly you felt your alternate worked better, you wouldn't be able to force it in place, unless you were a Microsoft developer and could recompile the operating system to your specifications. Thus, there was an uproar from other Internet browser makers about Internet Explorer being the forced default and there being no way to change this. Microsoft conceded, but the core of Internet Explorer still remains--you cannot remove it without compromising the whole system.
I suspect you cannot remove the 32-bit compatibility layer either.
Back in the days of anemic processors and scarcity of ram and hard disk space, I could see the merits of painstakingly removing every little piece of non-essential software from a system. But today? It's an unproductive concern. Additional RAM and hard disk space is cheap. There is a vast array of CPU choices out there that will run Windows 7 just fine.
I really can't see any need to press on the complaint of being unable to rid Windows 7 64-bit all traces of 32-bit programs, other than to just stir chaos for one's amusement.