This NM is by far one of the oddest NMs I've ever camped.
His spawn time seems to highly vary, anywhere between 2-6 hours (according to experience and some of my friends)
There's not much info. on here about how he pops. And honestly, I have no idea as well. I've seen both cases where I was taking out PH's single handedly then someone came in and stole Flauros, and then another time he popped right when another PH was supposed to. He does only pop in the main room, however.
The safest thing to do (and is what I do) is I kill all the Toramas in the room (hey easy farming, not to mention good skill ups) by grabbing them then pulling them into the main room. I take auto-target off and keep my camera looking around at all angles. Keep track of the Toramas re-spawn time (roughly 16 minutes) and never leave the main room unless you know there's no one else there. Even then while you're waiting, go outside the door grab a Wespe for Bee Larvae then go back in.
Overall, an obnoxious NM to camp. No wonder an NM with a 100% drop item still goes for so much on the AH in today's economy. He's obnoxious, no doubt about it.