I don't know all the ins and outs, but I'm not quite sure what all the fuss was about. It seems a little odd to me. The ports have been under "foreign" (British) control up to now anyway. The Congressional interest in intervening would seem to be against the free market/anti-protectionist stance that the USA tends to be known for, too. I think this is just normal business, in this case.
I suppose it will be said that this is about security concerns, but security will be in the hands of the same people as ever, such as the Coast Guard. Furthermore, I don't see the UAE bringing lots of workers over to operate these ports, I expect it will be Americans who staff them.
As for a terrorist threat, we had been told there was such strong evidence that Saddam Hussein's Iraq had links to the 9/11 attacks, the US and the UK invaded Iraq, the evidence dried up, and politicians had to admit there was no link. We're often told of terrorist threats whenever those in power want to manipulate our fears (although I'm not saying there is no threat whatsoever...). I think the issue about control of the ports has taken a strange turn, and is really about fear of things related to the Middle East.