Let's try this again.
Win32s contains a parser for PE files that is somehow able to load resources from a 32 bit .EXE or .DLL for access by a 16 bit process. As you already stated, Win16 does not have any memory mapping API. Therefore, there exists a kernel routine for extracting resources that does not use memory mapping.
Since at that time, it was popular to write such code as would compile and run correctly on both Win16 and Win32, there is a decent chance the code in question would run correctly if compiled for Win32. I can't see the code history, but it is plausible the code was adapted from WinNT 3.1's resource parser. If that is the case, than 640k's apparently nonsensical question suddenly makes a lot of sense.
[The Win32s loader is almost certainly a completely unrelated code base from the standard Windows NT loader, since the underlying kernel services are totally different. (Win32s supports memory-mapped files, and the Win32s loader probably used that underlying functionality. As far as I'm aware, standard resource extraction has always been done by memory-mapping, custom extractors notwithstanding.) -Raymond]