Sounds like nothing more sinister than a random act of madness. Seriously. The description leads one to believe the guy was more likely to be unhinged than yer actual boner-phydee hijacker.
Tell me something. What would be the difference between your scenario (likely of course) and that of a Yemeni with a clean record whose purpose was to perform this act for a specific purpose?
Is it possible that this nutter was put up to this act and after the dust clears and he serves his penance for his disturbance, most likely nothing with a good lawyer ("I had to go to the bathroom Imam, I mean your Honor"), and then provides a clear headed report to his masters of his 2 minutes at the cockpit door, the responses of the crew and passengers?
Look at it anyway you like, but if you are aircrew or involved with an airline, your job is also to look at it everyway possible.