I guarantee you everyone who downvoted me would be screaming for the murder of the CEO if a school shooting had actually happened, and it was discovered the platform sat on the information.
The process worked the way it should have. Police were alerted to a possible threat and promptly responded to verify.
The fact that this time it was just venting doesn't change the fact that statements like that should be taken seriously until they're proved not to be.
This was a teacher who was already around students when they made the statement. The response was appropriate.