any employer of worth would rather take a candidate that takes pride in their own self education and development rather than expecting the employer to foot the bill for career development. If a candidate can show they have learnt and can apply that knowledge, irrespective of how they gained that knowledge (whether it is a university degree, IT training or coursera) I personally try and do a coursera every few months to keep up with my own personal development program.
he is a cardioligist, which has very little to do with immunology or virology. An analogy ( for this forum ) would be a Ruby on Rails developer providing a critique on memory management in embedded systems. He can have his opinion, but just because he can be called "doctor" does not mean he knows everything about human physiology and pharmacology. If he had a strong opinion about heart health and cardiovascular disease (such as the debate around saturated fats) then I would give his opinion a high level of confidence.