But..
..who watches the watchmen?
Scientists at the NYU Tandon School of Engineering have designed a new form of application-specific integrated circuit (ASIC) designed to spot hidden vulnerabilities deep within a processor's design. Very few people run their own chip fabrication plants these days. Most processors are designed by one firm, which then …
For the fabless chip company they always have the option of decapping a chip and comparing what they see to the mask designs they'd originally sent off to the fab.
It's a lot of work and needs some specialised kit, but it's a certain way of being sure. Anything like this that gets you a similar result but more automatically sounds like a good thing.
The slice and scan technique certainly sounds like a better way to check to me.
If "naughty" fab were to add a delay into their "naughty" bit, so it only became operable after several gazillion operations, it wouldn't show up during electrical testing unless the implementation had been particularly bad.
Actually that electron probably can't travel a foot even in 1 hour...