How once charges into the line of fire or uses duck and cover tactics is likely due to the surroundings and amount of adrenaline coursing thru their minds.
But any defensive posture (and now even the likelihood of concealed carry persons at the lecterns) takes the killers motive into Phase 2.
Keeping them guessing and hard love is the solution.
This kid dismantled the system.
Adolescents love to do that.