Again, I'm just guessing wildly, but anything which scares people away from smoking is good in my opinion.
That's where I disagree, spreading misinformation as scientific fact causes people to lose trust in health authorities, and it fuels things like the anti-vax movement and flat earthers. The ends don't justify the means.
He has a large platform, and his audience is probably more likely to support Trump than Harris. So, him endorsing RFK is taking votes from Trump and helping Harris win the election.