the security concerns, whether it be with the ports or this WTC hypothetical, don't involve the Emir of the UAE personally issuing an order to blow anything up. the security concerns come from a foreign entity, in the middle east, being seen as the gateway for terrorists to exploit, to conduct such an operation.
as far as the WTC goes, I ask again - would you allow the UAE to buy the lease for the site from Silverstein. why not?