The industry seriously needs to start thinking about cockpit design for the future. If safety is of greater importance than cramming in 6 extra bums on seats then why can't staff members have their own toilet in a plane that has a variant able to carry 220 passengers? By making a flight deck just 45 inches longer and including a toilet in some kind of intermediate section so the pilots never have to "leave" the flight deck, will ensure there is no repeat of this kind of incident and will also prevent a would be terrorist from making a charge for any cockpit door when he sees a pilot come out.
If you think this is ridiculous ask yourself how you would feel as a professional office worker having to share bathroom facilities with over 100 passengers 4-5 times per day. It's a working environment for god sake, time to make it look and feel like one!