MrJ Stood near an Elementary School with a Loaded Gun,staring

Mr.J stood near an elementary school with a loaded gun,staring at the children and teachers,every day for a week.Could he be committed,even though he had a license for the gun and had not been seen committing a crime?

A) Yes,since he is clearly a danger to others.
B) Yes,but only if he is found to have a prior record of criminal activity.
C) Yes,but only if he is judged to be mentally ill.
D) No,because this would violate the principle forbidding "preventive detention."