protect Chinese diplomats’ legitimate rights and interests according to the Vienna Convention on Consular Relations.”
First question....why were they on the base?
Second question....how did they make it past the entry gate?
On a US Air Force base with tactical or strategic resources, they wouldn't have gotten past the pop-up security barriers. If they somehow had, AF Security Forces are ready and fully authorized to use deadly force. Past incidents of this type have not ended well for gate crashers.
I wonder if their car had electronics intended to penetrate base communications?