The way they handle everything else that doesn't fit their template: they'll ignore it.

He gets a hero's parade with ticker tape. The 'artist' gets suspended for drawing an un-permitted item. The construction paper gets a new job in the teacher's toilet.

Fifty percent of the people working in the typical public school don't teach. If they are not teaching, what are they doing there? If you're not teaching or sweeping up, you should be fired, fined into poverty for joining a union and swindling taxpayers instead of working at a real job, and told to go live under a bridge. That would allow school districts to give reparations to homeowners who've been forced to pay these numbskulls through property taxes. Property taxes should then be reduced by 2/3rds and frozen for fifty years. That should put a nice crimp in the entitlement mentality of education unions.

You forgot the part where he brandishes a pen and a scissors, claims he's pregnant, and screams loud enough to blow all the windows out of the bus.

That's kind of a drastic 'suspension'.

They are secretly angry that this didn't turn into another incident that they could use to promote gun (and who knows what else) confiscation. No dead kids ... no excuse to be authoritarian.