Current events don't necessitate an explanation of "why."
Students are killing teachers.
Sometimes with guns.
Other times not.
This is not a new situation but the magnitude and frequency of such acts in the modern day are beyond disturbing.
This petition is a suggestion of the old-school, 18th century compromise that got our founding documents out the door:
Modern teachers are, in extreme cases, targeted by their students and should be compensated for their exposure to this risk.
If you disagree with this spending for whatever reason the conversation must instead steer to prevention: Common Sense Gun Control
The general lack of respect for teachers regarding their pay and work environment is a separate, deeper, issue for this country, but protecting them at work should be obvious.