Why not?  Generally doesn’t mean always.  When I was in the Navy people intermixed both civilian and military systems constantly:

"Generally" not doing something means you're not "constantly" doing it. I would say your Navy experience does not correspond to what Okrand describes in his message. The Navy is not Klingon society.

The description of 'arlogh Qoylu'pu' suggests that most of the time Klingons will use "military time" in one way or another. Okrand suggests that non-military contexts are somewhat rare, and don't forget how Power Klingon tells us that nearly everyone wears military markings. The use of Qoylu'pu' among Klingons to tell the time will be rare.

We can easily imagine such contexts. A Klingon child is told to go to bed; he or she demands to know, 'arlogh Qoylu'pu'? A couple are in bed after mating, and one of them is due to ship out at 0730 hours; he or she might ask, 'arlogh Qoylu'pu'?

But if you're aboard your ship and someone wants to know when this week's in-flight movie starts, they'd say rep yIper, because "military time" is likely the standard throughout the Empire.

So the question is whether you can express not-on-the-hour times with Qoylu'pu', not whether you can substitute a military time answer in a non-military context. And that, we don't know.

-- 
SuStel
http://trimboli.name