Surely Mr Learmount has the right to express his opinion that “In my mind, it was simply not best practice. Were the passengers endangered by this? No. Did they have the same level of safety that they’d have had with four engines? Obviously not.”
Seems sensible to state that the same level of safety does not exist if one engine is shut down. What happens if a second engine fails? The failure of the second engine must reduce safety to a greater extent than the failure of the first engine.