Not that I have a particular dog in this fight, but perhaps because one worships the almighty dollar while the other doesn't? All being a good capitalist means is that you'd sell out your own mother if it made economic sense to do so. Ensuring the nation's security is not the sort of thing a public or private company does in order to make a profit.
I have yet to see a meaningful argument with evidence that a foreign based terminal operator does a worse job than a domestic based terminal operator when it comes to port security.
Where is the comparison between selling your mother for profit and CSX selling off their container terminal operations to focus on their domestic buisnesses? Show me where national security has been compromised?