Just SLF, but I understand what he was (probably) going through in a small way.
If you're suffering from some sort of mental "issue" you're often not aware of it and you think your actions are correct and justified.
I'm sure that after being locked out of the flight deck he was absolute in his belief that something bad was happening, and he was not the reason. In fact I think I'd kinda hope that someone locked out of the flight deck when something bad *was* happening would try really hard to get back in, so his attempt is certainly noble (if -- in this case -- misguided).
I have a reaction to a certain common drug and it makes me very agitated. The first time I had it, I was caught unaware and did some things out of character. Now I know and I make sure I don't take the drug, or if I do (it's unfortunately sometimes required) that I prepare those around me (and myself to some extent). Even knowing that I am not acting "normal", and why, it's hard to moderate your behaviour. Not knowing makes it almost impossible.
I have no real idea, but his problem may be a very small one, magnified by circumstance.
I'm sure that if I was on board that flight I would have found it alarming, but nobody died and the FO seems to have handled the situation as best he could in the interests of the safety of the flight (less so for the Captain, but let's face it if you have to choose between the two, you unfortunately may not be able to have 2 winners).
I hope the Captain is not too badly treated (I read this morning that he's been charged, and I hope that's wrong).
With only 2 people on the flight deck this must have been an interesting situation. Another use for flight engineers? I would also not have wanted to be the FO. I'm sure he was justified in his actions, and I'm sure he knows that, but I'd still feel pretty bad about what I'd done to a colleague.