I think archaic forex regulations are more of a blocker than free travel but what I meant is It can't be hard to agree to let diplomats travel easily. The impact is almost immaterial.
"That picture of the guy kissing the passport? I bet that wouldn't be happening if it were a meaningless non-milestone."
Somehow I doubt that that individual has any trouble obtaining whatever documentation is necessary to travel on official business. Short of some sort of political-spat between countries, all approvals for diplomats is probably rubber-stamped as soon as the details are confirmed/verified.