But access to those physical assets is probably also controlled with a list of who is allowed to access it. A list that it would be trivial to filter by ITAR status. If not, I have a quick vacation to take.
I'm not sure we're seeing this the same at all. ITAR restrictions cover a whole lot of things. I don't see why ITAR controlled assets would have a "list of who is allowed to access it". In fact, I bet that list doesn't exist. In my experience in the aerospace industry, awareness of ITAR restrictions was the personal responsibility of the employee. For most things falling under ITAR control, there was no or little protections or controls beyond this. For example: "this spreadsheet of components obviously cannot be sent to our IT subcontractors in India."
The discussion was about physical assets. I'm willing to bet areas of SpaceX with interesting physical prototypes have controlled access - and that access can be limited to US persons. If that's not the case, I plan to go on vacation to walk through SpaceX and play with their toys.
This is where I think the disconnect. ITAR includes many things much more mundane than cutting edge spacecraft prototypes. It’s still ITAR whether it’s strapped onto a prototype for the first time or on its 800th flight in production.
I think the disconnect is that I intended it more as a statement that SpaceX had physical locks (and/or some forms of access control) on their physical stuff. They have allow lists for various areas. So, at a rough level they can say ITAR hardware is in section 5, so they can only allow people in the intersection of "need section 5 access" and "US persons" in. Because the list is almost certainly computer managed.
It's kind of a joke that if they don't have locks I would play with the prototypes. Just because that's what I would seek out. But yes, ITAR can cover the boring and probably mundane as well.