It is a bit confusing.Originally Posted by T
The transitive use of "enlist" means to enroll individuals in the military. The intransitive use of "enlist" means to join the military. That would usually be "enlist in".
Most transitive verbs can be changed to the passive voice, but I haven't seen "should be enlisted". We tend to consider "enlist" to be an active decision rather than something that happens to someone. This would tend to rule out the passive voice.