It appears that from the school meetings the student was considered to be a low level threat instead of a medium level threat. The FBI distinguishes between 3 levels of risk:
“Levels of Risk
Low Level of Threat: A threat which poses a minimal risk to the victim and public safety.
Threat is vague and indirect.
Information contained within the threat is inconsistent, implausible or lacks detail.
Threat lacks realism.
Content of the threat suggests person is unlikely to carry it out.
Medium Level of Threat: A threat which could be carried out, although it may not appear entirely realistic.
Threat is more direct and more concrete than a low level threat.
Wording in the threat suggests that the threatener has given some thought to how the act will be carried out.
There may be a general indication of a possible place and time (though these signs still fall well short of a detailed plan).
There is no strong indication that the threatener has taken preparatory steps, although there may be some veiled reference or ambiguous or inconclusive evidence pointing to that possibility -- an allusion to a book or movie that shows the planning of a violent act, or a vague, general statement about the availability of weapons.
There may be a specific statement seeking to convey that the threat is not empty: "I'm serious!" or "I really mean this!"
High Level of Threat: A threat that appears to pose an imminent and serious danger to the safety of others.
Threat is direct, specific and plausible.
Threat suggests concrete steps have been taken toward carrying it out, for example, statements indicating that the threatener has acquired or practiced with a weapon or has had the victim under surveillance.”
The sticking point will be about the school’s decision to not call in the officer to conduct a risk assessment. A spokesman from that police department mentioned this to the local media.
I can only go by what I’ve read that there was something set up to assess student risk at the school but it didn’t happen? Even deemed low risk, a proactive policy is to screen any “ low-risk” potential shooters.