Intelligent people can arrive at different conclusions and can agree to disagree. I never said I was certain about anything. However, his past history, his own words on the topic, and his ability to cognitively function at a relatively high level for lengthy periods of time lead me to be reasonably confident in my conclusions - not certain, just reasonably confident based on the evidence I have seen.
You stated you were open to any possibility and then dismissively ended the debate. Apparently you are quite certain of your own opinion. No disrespect here either.