America is in a sad, sad state when there is no recourse for something like this. What are we, afraid of diplomatically insulting an Islamist dictatorship?
Diplomatic immunity is part of international law and exists for good reasons. See the Vienna Convention:
https://en.wikipedia.org/wiki/Vienna_Convention_on_Diplomati...
If you think that concept is wrong, why not address that or argue for the US to be exempt from the Vienna Convention?