A scientist saying something, if it is their field, and they have gone through pere review, should be taken seriously but others are and will continue to check his work to make sure the theory hold up under all conditions.
There are scientific assertions or theories that it is difficult to see how they could be refuted, heliocentric theory will not be over turned, evolutionary theory, cell theory, disease theory, and many others are so finely known that no one thinks they will ever be overturned, maybe refined, but that would be tiny changes at best.
I to tend to be rather abrupt bu