I can't see a problem, as long as the chips are not fraudulently resold. Beyond not using a resource in the first place, reuse is the gold standard in sustainability.

As an engineer, I wouldn't use second hand components for prototyping. When prototyping you need to eliminate as much uncertainty as possible. I'd consider using second hand components in production, provided there is a cost advantage, supply is reliable and my production line includes a test that would pick up faulty components. Even then, I'd be monitoring failure rates and reverting to new components if elevated failure rates caused costs. There's an argument that (well handled) second hand components might even have a lower failure rate than new as they have been burned in.

I'm guessing this company is targeting specialsied repair rather than production. Sometimes complex parts are no longer manufactured and the only option is second hand (often at a premium price).