I think he's saying that during interviews the candidates were being asked to dive deep into their preceding employers' tech stacks. Which does seem to be asking them to tread in dicey legal waters in a coercive situation.

I see. Always stuggled with this. I think design interview on hypotheticals is better. Or have you used X with follow up questions about X? Probably OK to say we used kubetnetes. But not OK to describe inner workings of a custom controller that speeds up their workloads even if candidate wrote the code.