To say Old Joe has a responsibility here is absured. He has stated what he was told by the shop owner and the gun owner. We should inspect all our firearms but does that mean we trust the guy shooting next to us has done the same when he offers to let us shoot his new acquisition?? We all assume that a gun we purchase from a gun shop is in decent condition and yes common sense says take a very good look at it. If we distrust any and all guns then we should not shoot any other than our own. Old Joe is a VICTIM and should be treated as such.
The idea Old Joe would be laughed out of court is wrong, I remember the HUGE settlement to the person that bought a motorhome, put it on cruise control, left the drivers seat to go make a sandwich and crashed. Settlement was staggering and the defence was it didn't warn you in the manual you couldn't do that. Old Joe lives in the USAwhere litigation is viewed by some as a national sport.
This is a legitimate claim and would be judged as such.