[禁止「きんし」] => Don't do N4
Can, Should, Must
とは[裏腹「うらはら」] => Contrary to A, opposite of A, ... N1
Contrast/Surprise
を[禁「きん」]じ[得「え」]ない => Can't help but do A, can't hold back from A (emotional response to something) N1
Will, Decision, Doing