If he likes science, try telling him about the hierarchy of evidence Hierarchy of evidence - Wikipedia
We use it to filter what's worth paying attention to, in terms of how robust the evidence for something is.
Don't talk about MH or drugs, try to apply it to the news or technology.
Then when you can see that he can apply critical thinking to abstract stuff that doesn't trigger an emotional reaction from him, try looking at healthcare.
Once someone can see a framework for decision making has an application in real life, it can help them with other things too.
You're a good guy.