"more likely" is an assumption itself. Which could be correct. I do not know. I know several organizations, including the one where I work, where a lot of debate has gone into which security measures should be adopted and why (including, where to place cameras, what type of ID should be used, what access control system to adopt, etc.). You're right in saying that evolutionary accident or whim can be the causes for many policies. But I also know for sure that that is not always the case.

Having said this. I did not say the no-hat policy is good or bad. I do not know.
I said that it could be good if backed up by real studies and evidence, and it could be wrong if based on no real factual reason. Both scenarios are possible as far as I can tell, and because of that I would not dismiss the no-hat policy without further info.