I had a province nap with a kingdom 2 ages ago that I was in war with. Given that we lost 50,000 acres in that war, I don't think anyone on the server considered it a fake war.
Goes back to the suggestion made many times, as long as it costs hundreds of millions of dollars for large provinces to build their lands, they will make province naps with eachother. Fix this problem and you'll no longer have province naps to deal with. The goofy deals made often are made as a result of things that the devs should fix, that go unfixed.