I think it would be rather difficult to persuade the CAA and the court that my 500hrs and private ticket allowed the ATPL with 10k hrs sitting next to me to walk free because he was a "passenger"
Are you sure you've got a "ticket"?
The plain and simple fact is that when you assume command you do just that. It is not a command that may be relinquished at a convenient moment just because the guy sitting next to you happens to hold qualifications equal to or superior to your own, unless you ask him to do so and he agrees.
You must accept the responsibility that goes with that command, full stop.
Apologies for digressing from the original posters topic, you have my utmost sympathy Sir.