The main problem I see with this post is that it assumes that it's always advantageous to find out the truth and update one's beliefs towards greater factual and logical accuracy. Supposedly, the only danger of questioning things too much is that attempts to do so might malfunction and instead move one towards potentially dangerous false beliefs (which I assume is meant by the epithets such as "nutty" and "crazy").

Yet I find this assumption entirely unwarranted. The benefits of holding false beliefs can be greater than the costs. This typically happens when certain false beliefs have high positive signaling value, but don't imply any highly costly or dangerous behavior. Questioning and correcting such beliefs can incur far more cost than benefit; one can try to continue feigning them, but for most people it will be at least somewhat difficult and unpleasant. There are also many situations where the discovery of truth can make one's life miserable for purely personal reasons, and it's in the best interest of one's happiness to avoid snooping and questioning things too much.

It seems to me that the problem for uncompromising truth-seekers is not just how to avoid invalid reasoning leading to crazy false beliefs, but also how to avoid forming true beliefs that will have negative signaling consequences or drastically reduce one's happiness. Now, maybe you would argue that one should always strive for truth no matter what, but this requires a separate argument in addition to what's presented in the above post -- which is by itself insufficient to address the reasons for why people are "afraid to think fully about certain subjects."