A combination of several factors, IMO. A group of people that look at this as yet another way to score political points of their own at the expense of the administration, as well as (so far) an abyssmal job by the administration of explaining the details, as well as a stunning lack of awareness on their part of just how most Americans are going to look at this post 9/11.
But most of all, once again, the media has to take most of the blame. They have completely abdicated their duty to inform us about the issues of the day, choosing instead to serve as the propaganda arm of the DNC and help them push a radical left-wing agenda, the only goal of which is to completely destroy the Bush Administration and eliminate the Republican Party as an electoral threat forever. So instead of getting news and information about this port deal, all we get is continuing coverage of Dick Cheney's hunting accident, as well as the vilest rumor-mongering about the accident being passed off as news. Oh yeah, we also get our daily dose of leaked national security secrets.
Of course - the media. They're left wing liberals, and just like the other Dems, Dem political success means more than our security, economic success, or anything.
But what's with the Conservatives who think trashing the Bush Admin. is a good move? It's fine to argue priorities and programs, but on some issues (like this port deal and immigration policy), it's been more trash from the so-called Conservatives than from the Left-Wing moonbats. If they really think a left-wing admin. would be satisfying - well, all I can say is that they're too young to remember Carter. :-)