Wouldn't B's publication of the information make it by definition no longer a trade secret? It is now public knowledge, regardless of whether the current or former engineers might be liable for the original leak.
Any other interpretation would mean trade secrets have essentially infinite protection/NDAs apply to all of humanity.
The NDA doesn't apply to people who haven't signed it, but copyright law does. If you know the material you're receiving is under copyright (eg proprietary source code), and you publish work based on that copyright material, the fact that it's now widely available is not an effective defense against claims of copyright violation.
Person B in this scenario hasn't violated the NDA, but they could be sued for copyright infringement.
The point of a clean-room implementation is that the only thing passing from A to B is a detailed specification written from scratch, because functional details cannot be copyrighted.
Which I think you know, so I don't understand your argument.
You said in another comment "However, this specific thread is about the scenario where an employee has inside knowledge and is passing that knowledge on to the implementer."
It being proprietary and/or secret information doesn't affect the copyright of the clean-room output. If there's trade secret implications those are worth discussing, but as a separate issue.
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
The argument is not esoteric. An Apple employee working on a reverse engineered GPU driver might (intentionally or not) incorporate internal knowledge that they are contractually obligated to keep secret or write an implementation that is too close to proprietary code they had access to, to the point that it could be argued that it is a derived work.
This sort of thing has always been a concern for projects that re-implement some existing piece of software, e.g. there were concerns early on during development of the GNU project about people contributing after having been exposed to Unix source code. Similarly, it is an ongoing concern for the Wine project[1], as well as ReactOS. The later even had a code freeze and internal audit in 2006, after allegations came forward that code had been derived from disassembled Windows binaries[2].
Exactly! That’s why companies create a clone every time they hire someone, put a clone into vat, and upon person quitting, the person is disposed of and the clone is sent to his family to take upon his role, without leaking company’s internal knowledge.