This is a terrible argument. It starts with something we have high confidence about (yes, smoking is proven to be bad), and the fact that there were companies that profited from it, and then extends that to say that doubt and epistemic uncertainty are bad.

And therefore you should believe the author’s other hobby-horses, because if you doubt it you’re the enemy, or a sucker.

Being able to recognize what you don’t know isn’t going to help you quit smoking, but it helps you from falling for conspiracy theories, and that’s important too.

(A good way to learn to live with doubt is to collect questions you don’t have good answers to yet.)