I don't agree with that statement.  The ability to think critically or rationally isn't inherently tied to one's trustworthiness, in my not so humble opinion.

Of course the earth is round, more than 7000 years old, and orbits the sun.  I know all these things, but a lot of people choose to argue these facts due to their spiritual beliefs, lack of knowledge, or learning disabilities.  I don't think that automatically makes them untrustworthy.