Gerard C and BOAC:
I seem to recall that there was a segment of CVR that showed Commander Dubois asking PF FO Bonin if he was qualified to fly as PIC, to which Bonin said yes. IIRC all that, Dubois then told Bonin in RHS that he was in charge.
I can’t find the CVR transcript portion with that in, but if I’m wrong no doubt somebody will correct me.