People can beat their gums speculating all day long, but until the crew's story is published that's all it will be. Was there a pin problem? Was there a 'gear up' problem? I once had it on B757 where the tilt switch failed, but then the trigger solution worked. I've known of at least 3 occasions where the nose gear pin was left in. How? Because the techie had his own pin, he was then distracted, and there were 3 nice shiny pins still in the flight deck. Horrible rainy night so I guess the crew walk round was swift.
There could be a respectable reason for this event. I hope we do hear the truth, but don't hold your breath. Maybe someone has an inside contact?