It's not even about union jobs.
The company that's been running those ports has been British for years. The only change is that the company that runs the ports will be moving it's home base from one allied country to another. That's pretty much the only change. They're not going to import thousands of dockworkers, and no Americans are going to lose jobs. On top of that, this company isn't responsible for security anyhow.
On top of THAT, the contract was fairly bid and won and the people in the US responsible for the bidding process are 100% non-political, and the president and his inner circle didn't even know about it until the media and a few congresscritters blew it up out of proportion. So claims that it's croneyism and political money laundering are pretty much BS.
What it comes down to is that in a fair contract competition, one foreign company beat out an incumbent foreign company, and congress went beserk over pretty much nothing. Bush had to weigh in because it would be a HUGE slap in the face against an international trade partner to say that they can't get a non-security related job simply because they're Arabic, not British, and because congress is using their national culture as an excuse to block them from winning a contract from another non-American company.
I'm with Bush on this one, 100%. It's a debate being waged by the ignorant and those with political goals to be gained at the President's and the UAE's expense. It has nothing to do with security or international bribery.