How is a bomb threat not a life threatening emergency?

As of 2:30 P.M. today, DePaul students, faculty and staff had the all-clear to return to the library.

In a letter to all DePaulians, Media Relations explained the situation, saying that DPU Alert is only used in life-threatening emergency. Can someone explain...how is a bomb threat not a life threatening emergency? While I ponder that, here's what they said:

What Did DePaul Do?
When DePaul learned of the threat, Public Safety immediately notified Chicago Police to assess the situation. After a preliminary investigation, a precautionary evacuation was ordered. DePaul activated its public address and electronic message sign system at the Lincoln Park Campus. A large number of Public Safety and Chicago Police officers were on the scene to personally notify those directly affected, and direct those outside the building away from any potential danger. DePaul also sent an e-mail to the desks of all employees to alert them to what was happening and posted the information on its home page, DePaul’s main source of information in an emergency.

Unfortunately, bomb threats are a routine prank designed to disrupt activities at many institutions. DePaul takes every threat seriously. It calls on the expertise of the highly trained Chicago Police Department to evaluate the danger level and then responds accordingly, always ready to take the next step if and when the situation were to become more serious. DePaul must balance safety needs with educational needs and make the best decisions based on the information available.

Why Didn’t You Receive a DPU Alert?
DPU Alert notifies approximately 30,000 people in the DePaul University community simultaneously in up to three different ways: telephone, e-mail and text message.

This system was established for use in life-threatening emergencies with immediate danger and is not designed to be a primary alert system. First responders, who are most likely to be Public Safety officers and Chicago Police or Fire personnel, will direct those in immediate danger to safety. Then, DePaul’s public address and electronic message sign system will be activated in the area(s) affected. DPU Alert will be used if the situation is determined to pose imminent danger, and will almost always be the third notification to those in the area when a decision is made to activate it.

DePaul evacuated the library as a precautionary measure. A large number of Public Safety and Chicago Police personnel were on the scene directing people away from danger. No other buildings were affected and no classes cancelled outside the library. When the evacuation was ordered, there was no need to disrupt the business of the entire university community. However, emergency communication staff were prepared to issue a DPU Alert if the situation were to escalate. Thankfully, that did not become necessary.

DePaul regrets the inconvenience this unfounded threat caused.At this time no other buildings are affected and classes and activities in all other Lincoln Park facilities will continue as scheduled.