PNF doesn't make any reference to his instruments (other than speed) being out. Remember it was the instruments on his side being recorded, and the report makes no mention of instrument failure. Also, his rising alarm regarding the Captain's return could suggest that he could see exactly what the aircraft was doing and didn't like it one bit.
To be simple:
You are PNF in an C172
You see (instruments) that with no doubts the aircraft is climbing
You ask the PF to stop climbing or more you ask him to go down
The PF answer you "yes ok i go down"
Again you check the instruments .. and see that the plane continue to climb .. and of course as nothing indicate an instrument failure .. you become concerned
For the demonstration only (as you can check your own yoke
) .. you check the PF yoke and see he pull the yoke in his stomach ...
In the A330 ...
It was already an instrument failure (unlike in the C172) ... it was a positive answer of PF (like in the C172) ... and when you check again instrumentation .. the instruments show the aircraft continue climbing
You check your stick ?
You check the stick of PF ?
You put handcuffs on the PF ?