Re: Does Star Fleet not run psychiatric examinations on its recruits?
Being shy, intoverted, is as you say not a mental illness.
As an introvert, I'd agree with this. I think introverts can be harder to read because they don't always broadcast their thoughts for everyone to hear, but that's not a sign of a behavioral problem or mental illness. One of the things modern psychiatry has tried to correct is the idea that because a person is poorly understood means said person has something wrong with them.
"He clapped his captain—his friend—on the shoulder. Yes, this man was very much like James Kirk, in all the ways that mattered." --Christopher L. Bennett-- Star Trek: Mere Anarachy, The Darkness Drops Again