The folks here that can't imagine how this is possible and are talking about it being 'fishy' should know something: Gear up landings happen all the time despite warning systems, because sometimes people don't follow checklists.
I know folks who will go out and practice stalls, and when they pull back the throttle and their airspeed drops past a certain point, it becomes second nature to reach out and silence the warning horn. The people with warning systems that land gear up usually report that they didn't remember hearing the gear warning, and a bunch of those are probably because they instinctively reached out and flipped the switch without thinkign about what the sound was trying to tell them.
What's unusual here is that it happened with two crew instead of a single pilot. This is a failure of cockpit resource management, nothing else. The 11 hour flight that preceeded the landing probably didn't help, but that's what checklists are for. People who go through the motions or skip checklists are the ones who get into this type of trouble.
Now start your timers, I'm sure Golfer will be in here soon to do some more "rofling' at me having the temereity to talk about "his" subject along with more jabs at my ultralight thing from 6 months ago.
Some of the more pessimistic people in the canard community say that there are two types of people flying retracts. Those who have had a gear up landing, and those who will. The nose gear on the LongEZ and Cozy is retractable, and there's a handful of people who landed on the mains, then commented on how they watched the nose go down... and down,.... and keep going down. Apparently, landing a LongEZ on its nose is an effective way to make the first turnout, it stops it pretty quickly.
You know how to tell when you've made a gear up landing? It takes full throttle to taxi.