The danger of an open mind is malicious entities seek to fill it with trash and slam a lid on it.

Remind him to question everything, every motive. Introduce him to moderate information that question both sides of an issue. Some have mentioned Tim Pool. He is a good starting point, even if he is foolish at times. He still expresses when he speaks opinion and bias, allowing his audience to know they can take their own look at something if they choose.