Obviously the F/O was concerned, since the captain had failed to return to the cockpit and somebody with a strange accent was asking for access to the cockpit, that perhaps somebody had a utility knife to the captain's jugular. That could well have elicited the F/O's name, rank, serial number, SSN, name of first-born and pretty much anything else needed.
Don't know what your arse has to do with it, nor has anybody claimed that the F/O was "so scared"--he seemed to be pretty cool in his R/Ts--and it seems to me his reaction was neither "rubbish" nor "out of proportion."