I think the issue would be mainly that people fail to realize the nature of what they're corresponding with, and take things from inside their heads and behind the walls, and put them into the chat?
No one is "corresponding" trade secrets outside of their company. I recommend reading up on ITAR and the resulting culture it has created around aerospace info.
Note that google cloud has an itar-compatible gemini pro and google drive / docs - so, people do talk to it - and google is of course contractually obligated to not export it, nor to learn from it.
This is very different that AWS fed-gov bedrock thingie - where AWS promises that the models are running on hardware dedicated to you, with no external logging, etc.
Maybe a better way to say it would be, no one is talking to AI that isn't on company serves, managed by that company personnel.
My overall point being, no one is submitting design files to ChatGPT for analysis or emailing their friends in China test reports to get a second opinion on the experimental results.
> google cloud has an itar-compatible gemini pro and google drive / docs - so, people do talk to it
A lot of aerospace engineering is touch and feel. Someone has a "sense" for when to do the next step, and how to finagle the part so it comes out a particular way. They can train someone, if they apply themselves intently. But they probably couldn't explain it in words if they tried.
Don't forget these companies are both civilian and millitary contractors. These kind of information will stored in separate air-gapped computer systems.