Can a student, who is a ltc holder, be kept out of a classroom on the grounds that the students presence and his/her concealed handgun are making others feel unsafe?

No,

Explanation:

In united States, the right to bear fire arms is protected under the 2nd amendment of the constitution.

The only situation where a person can legally be thrown out from a certain social setting is if that person is directly disrupt the activity in that group with the weapon.

From the passage above, the student who held the concealed weapon does not seems to actively do something that disrupt others. This make the class does not have any legal / solid ground to kept that student out.

disorders of the brain include both behavior disorders and other psychiatric illnesses. the primary difference between a behavior disorder and another type of psychiatric disorder is the presence of choice. psychiatric conditions are considered to be involuntary while in behavior disorders, choices are essential.