Some bright spark has posted a comment that says, "Wow fixing the game before release. Thats (sic) something new for you DICE!" which is a bit cruel but does show exactly why DICE has delayed BF4 Naval Strike on PC.
This is the official word as well, horse's mouth stuff: "We are delaying the launch of Battlefield 4 Naval Strike
on PC", says a spokesmouth. But why?
"We’ve detected an issue and it needs to be solved. Quality is our number one priority and we will not release Battlefield 4 Naval Strike
on PC until we feel it meets the highest quality level possible. Once we have a confirmed date for PC, we’ll be sure to update those players on our official channels. We appreciate your patience and look forward to seeing everyone on the Battlefield."