Earlier quoted context omitted.
"Person A was under NDA, so we got them to pass their knowledge to person B, then had person B do the work - that's clean-room, right?" Judges, as far as I know, do not generally take kindly to such arguments.
So what if person a and person b are unrelated and person b found it on their own? There are countries in the global south that never had an industrial revolution and don't speak English and never had factories for export nor made anything in a factory industrially that isn't building material and food and maybe fuel for local consumption so they've never had an IP infringement case
That's what's referred to as a "clean room implementation" further up the thread.
However, this specific thread is about the scenario where an employee has inside knowledge and is passing that knowledge on to the implementer.
Legally speaking, a clean room implementation has much better defenses from claims of copyright violation.