I don’t think this is an age issue, perhaps an American cultural issue, but I’ve interviewed several candidates who represented skill sets on paper and then admitted they have not used, and would not recall how to use those skills in any significant fashion. And that is outside of the design career, it can apply to anyone.
For example: My old boss used Pro Engineer, but in the late 90’s. He too had 20+ patents to his name - if you asked him to open a modern version of Creo and sketch out a box with a hole in it, it wouldn’t happen. Did that make him a bad director? Not in any way shape or form - but having had a skill set and still having a skill set are not always the same thing.
Your treatment by said employee is not justified by any of this, but putting the shoe on the other foot, if I was hiring for a position and I knew that position would have to mentor and/or do tactical work, I would probably require some type of skills test or clear demonstration of what skills you had that were up to date. As an employer, you wouldn’t want to hire someone and then find out on the first day they can talk the talk but not actually execute the way they said.
Google is one of the biggest tech companies in the world and no one gets in the door with out some type of demonstrated design exercise - so it’s not to say exercises/tests are uncommon or frowned upon, but employers should be forthcoming with their expectations.