The AI may have been. But so do the humans. You don't know what they did or did not saw over the years, especially before they were employed with you, especially when the topic is RE of some project that has OSS components in it. Chances are, they used or otherwise seen those OSS components, or their clones/copies/forks in the past. This is meaningful because presumably you're not choosing any random SEs for the job - you're choosing people with experience in the same area as the project you're RE-ing, to have a remote chance of completing the work.

So with people, much like LLM, there's a good chance they saw the same code and papers the implementers of your target did, and whether your work is clean-room or not boils down to believing or disproving they were not aware of the association.