Right at the end of the Businessweek article it says "In the three years since the briefing in McLean, no commercially viable way to detect attacks like the one on Supermicro’s motherboards has emerged—or has looked likely to emerge"
Even based on the little we do know, that is bollocks. Elsewhere in the article they say "the implanted chips were designed to ping anonymous computers on the internet for further instructions, operatives could hack those computers to identify others who’d been affected". So there is a commercially viable way of detecting the chips. Good old-fashioned traffic monitoring.
Sounds more like all those old chain emails that used to go around about viruses that "nobody could detect", encouraging you to forward the email on to as many people as you could to warn them. GCHQ and NSA probably have enough taps on enough lines to do this for us.