In a courteous way I asked why he had decided to give up the wonderful automatics available and instead just sit staring at the instruments when he had such a glorious night outside with views even!
No offence intended but it sounds like you were part of the problem here with the fact you didn't seem able to say "I'm knackered, would you mind keeping the autopilot in until 1000ft?" Did you discuss it after landing?
Unrelated to this thread but the smoothest flying I ever witnessed from another pilot also gave the impression that she wasn't touching the controls, even though she flew a perfect CDA from top of descent with all the automatics off.