One: what difference does it make if he runs Windows or not? Would he be more eligible to be a hacker if he was running AmigaOS or BeOS or what are you trying to say?

Two: The article did not say anything about running a executable file. It said he had downloaded a zip file called ""Georgian-Nato Agreement.", not that the zip contained exe's. There are other files than just executables that can contain malicious code, for example the guy himself is supposed to have used XDP files.