I don't think the issue is necessarily 'military hardware'. I believe the issue that the article addressed are the commercial chips *inside* hardware - military or commercial, used for military purposes. A grid of commercial servers used for military purposes is 'military hardware', despite it's commercial origins.
I would not be surprised if -- for example, and I'm making this up -- the latest Intel processors had a hidden RFID capability supplied by the DoD that would cripple the processor if it received a particular coded signal. With a chip budget of billions of transistors, who could ever find something like that *if* it existed?
Or maybe a Chinese-made motherboard with the same capability. Or a controller chip made fabricated in Eastern Europe. Or a software device driver with hidden military functionality. Or whatever. The point the article tried to make is that today's chips, motherboards, and software are so complicated, and are designed and produced by so many countries (not all of whom are necessarily on the same side) that hidden functionality could be built into them and nobody would ever notice them -- until they were activated.
There is even the possibility that multiple kill functions exist in a single computer - each controlled by a different organization.
Military hardware or not, imagine the havoc you could unleash if you had the capability to cripple all the Wintel computers in a given country...