I've never seen anyone cloak grief, yet. It may exist, but I haven't seen it.
I have entered a PvP match where I was the only Klingon and the Feds were shouting for a nonexistent "us" to uncloak. I don't. I do say in zone chat that we all aren't here. I full impulse around trying to see if I can find other Klingons. It can take two or three minutes for all Klingons to come in sometimes. Those 2-3 minutes can seem like an eternity and "cloak griefing" to the Feds.
Once the team is formed (if it is a good PUG) we go over and see the composition of the Feds. We spot and call out the escorts. This can take up to 2 minutes as we fly to them and chat about the best way to open on the escort and the second ship after the escort.
These four minutes are hell for the Feds, but don't blame us, blame the queue and our playing the game correctly.
After that, once we open up, we only cloak to escape destruction and to heal/regroup/set up the next attack.
I did enter a HvH arena and saw no one. I uncloaked and flew around. No one. After two minutes I understood what the Feds where talking about, but as annoying as it was, I was uncloaked and no one shot at me. That's because no one was there. After a few more minutes a few ships opened up on me so I cloaked. Some of my team finally got in and the match began.
While I admit that some "less than brilliant" Klingons might Cloak Grief, I think a more reasonable scenario is that an incomplete team of Klingons started fighting, lost, and one or more of them left for some reason (could have been a good one, like real life issues). After that the remaining Klingon waits for more to show up. And the Feds think they are just hiding for spite.
I do know that when with my fleet (in a premade and vent) we sometimes cloak and speak a little strategy if the fight is close. The opposing Feds are obviously good or better than our team so they understand what we are doing. We take a minute, it may take 2 to set up. These Feds might joke about it, but they understand what we are doing.
Since I see no reason for cloak griefing, I'm not really sure that that's what happens when Feds don't see Klingons. Maybe they're just not there.
One also has to consider the patience factor. Sometimes I'll see a good poker player think for a while on the river before doing anything. Usually one bad player loses patience and says, "Well, call, fold or raise!!!" The bad player isn't even aware of what there is to think about, and no one says anything.
Some Feds may equate PvE to PvP. Let's go, let's go. Let's fight, let's fight. Pew, pew time. Some people feel the 30 seconds as 30 minutes.