http://www.singularcycles.com/gryphon.html
As to why you might want to ride off-road with drop handlebars, there are a number of good reasons.
A more natural angle and position of the hands, allows you secure purchase on the bars without needing a death grip.
A more secure feeling on the bars, no tendency to slide off the front. In rough terrain the hands are simply forced further into the hooks.
Variety of hand positions. Riding long distances with the hands in one position can cause them to become numb. Drops allow you to sit up and ride on the hoods or the tops to rest both hands and body.
Sure, it's a 29er but I don't think that really matters to the general thrust of the points.
I rode one round a few bits of Lee Quarry at the Weekender. It was great, including in the drops over the rock causeway.
I went all Victor Kiam as well :poor now:
I suspect (knowing little about it all) that it's more about running drops with 26 wheels on a bike that's made for the purpose. Like most things, trying to shoe horn drops onto bikes nowadays that are set up to run big forks and have fairly "sit up" positions (hence a higher headtube) probably isn't going to feel great.
Plus, I imagine drops and suspension forks are likely to feel weird, especially when you're in the 125 to 150mm travel bracket.
Lee McCormack mentions that human nature is to protect your head. Sticking your head low and forward, especially in steep situations, is counter-intuitive. It's something he recommends working through to master the attack position. I'd guess drops would make working against these natural instincts even harder.
Edit – they were flared bars as well, rather than being true roadie drops. Fairly broad as well.