I have had to deal with a pilot who goofed. We were together in a two seat aeroplane at the time and luckily I was able to recover from the goof.
I decided it was the sort of mistake any of us could have made (in his circumstances at that time) and that he was the least likely one in the team to make that mistake again.
He never did make that or any other mistake and I never mentioned our incident to anyone else.
Judgement is needed. Assuming the Captain fully accepted he should have spotted the unlock then he would have my total backing all the way as he will never make that mistake again. . If he wants to blame Airbus or the mechs I would feel very differently.