I'd say it's because componant parts for the MAUL are made in...

I'd say it's because componant parts for the MAUL are made in the US as stated in the bulliten so no surprise the US Govt want a say in who gets the complete weapon and also that this approval is for this contract only.
I remember a couple of AGM's ago been given the MAUL barrel to hold (surprisingly light) this maybe because of special materials that can be sourced and made in the US
only, if not the barrel then obviously other parts are and as said in bulliten MSI had an important part to play here.
Cheers,
mrdog.