Honestly, I can't understand why a fat ELF would be need. Just wrap a small shell script around two or more binaries. All it would have to do is detect the OS (uname anyone?) and unpack the right segment. It is messier, somewhat, but it works.

Ah yes, blame the fact that they ran a program on an open source operating system. It looks to me like the software that ran the surgical operation wasn't open source at all. It seems it was all closed source software that was doing anything except running the computers. Although I am a bit lost; I don't seem to remember when Microsoft went into the medical field.