There’s no “science”. There’s scientists, each of whom have a different opinion and viewpoint and expertise - I can find eminent and qualified scientists who have written articles saying there will be a second wave, there won’t, there will be a vaccine, there won’t, it’s risky to lift lockdown, it isn’t....
It’s like the joke about economists - put ten in a room to discuss something and you’ll get at least eleven opinions.
All credit to him for sticking to his view, but his remit is rather narrower than that of government as a whole.