I think it's not clear from the article why they left (e.g. could be anything from retirement to going to work at another firm/contracting to being fired to switching careers), and likely it's going to be a mix, plus not all were previous Ford employees. Similarly the "AI" isn't clearly defined (but like you I would be surprised if it were LLMs). I suspect though why the article exists (and a possible source of your downvotes) is signalling against "AI", which if Ford wants more expert employees (given their issues), is something Ford wants to present.