The main issue always was Dragos' inability to isolate any suspicious artifacts besides "I can't burn CDs!".

Basically his story required there to not only be firmware malware that could infect a wide variety of devices, but for said malware to somehow exist in a part of the firmware/BIOS chip which couldn't be dumped for examination. Even if such a thing existed he still could have tapped a logic analyzer onto a USB cable, plugged in some fresh hardware, and captured what the malware did.