They didn't have the code for the offensive program, they were creating the emulator to run it on a different architecture.
> offensive program
Agreed.
Which optimizer replaces a 64k loop with 64k instructions?
Ah, yes. Microsoft's!
There is no indication that the compiler that produced the code was Microsoft's. Actually the article hints otherwise ("[...] whatever compiler was used to compile this code").
Who has been validating that approach to solve their own optimization target?