Does this stop the head of Volkswagen from traveling to the US to work-related meetings with leaders of Volkswagen US?
No, meetings are fine. Any business-related work in US is fine, as long as you're not getting paid by a US company for it. So, going to meetings, conferences, training, etc. is all fine. There are some grey areas when you work for a foreign subsidiary of a US company and you're staying for a week or longer at the US office... then it's often up to the security officer at the border to determine whether that's considered work or not -- many companies end up getting their employees short-term work visas for such trips, just in case.