My own view is that it was a really bad judgment call by the whole crew.
Engine shutdown/failure at the beginning of a long leg such as this should have been a return.
If this failure happened after several hours into the flight then yes continue after all other possible problems have been considered.
I have been reading the post for quite some time and even had discussions with the managment of my present company.
I was told that any pilot that did this here would be terminated immediately.
This is stretching the regs too far.
Maybe BA has a different view.