Expertise in Pilotage is a mix of Knowledge and Technical Skills. Knowledge comes from being taught or exposed to the relevant conditions, procedures and events that come with aviation. Technical skills come from practice, procedural and systems knowledge. All of this is achieved through time in the job aka hours in the logbook.
When that is considered, a 20,000 hour 747 Captain would most likely be considered an expert in his field especially if most of his hours were in Airline operations and flying large jets, after all he's not going to be a 747 Captain on passenger flights without some decent experiences and training. The 'Idiot' captains being referred to for poor CRM etc are poor in non-technical skills. They lack interpersonal skills to appropriately lead a crew in time pressure situations, is this desirable in a pilot? no, does it mean that the pilot is not an expert in 747 operations, also no.
Medicine is no different, Expert surgeons are often aloof characters with poor interpersonal skills. But that matters nowt if they know their subject inside out and can wield a scalpel with grace.
Now applied in the case of Covid, is that worldwide many studies by qualified experts have been conducted and found what we know today. The odd outlying expert will have opinions that differ for whatever reason, but, the vast majority back what we are doing, and hence we are following the consensus of most experts in the medical field.
Expert pilots make mistakes and get caught out like expert surgeons do, and somebody might die, property damaged. Expert just means they have greater knowledge and skills than a Novice, it does not make you infallible.