From the text:
Windows platforms may be troublesome to maintain, but most civilian sysadmins simply wouldn't believe the resources the navy can throw at problems. A present-day Type 42 destroyer carries at least four people who have absolutely nothing else to do but care for the ship's command system. As of just a few years ago, this was still a pair of antique 24-bit, 1MHz machines each with about 25KB of RAM.
There may also be perfectly valid criticisms to be made regarding Windows usability. When triggering missile decoys with seconds to spare, one doesn't need a superfluous pop-up box saying "Do you want to use soft kill?" with "Confirm" and "Cancel" buttons. But this kind of thing isn't going to faze you if you're used to entering instruction sets such as "PE L5414.10N L00335.67E R6000 TMDA [INJECT]" from memory without backspace or delete. During combat, mind. The one group of users to whom Windows 2000 might look pretty marvellous are RN warfare operators.