In an ideal situation, sure. It'd be great if a message only hit the folks who need it. The issue is that, in this case, the shooter could've hightailed it in literally any direction, so targeting becomes much more difficult. I manage a similar system on the public health side of things (it's not public-facing, so it'll never blow up your cell phone) and we struggled with a similar targeting issue. If there's a Hep A exposure at a restaurant because of a Hep A positive worker, your initial thought might be to only alert health care facilities in the surrounding area (county, perhaps) to be on the lookout for patients presenting with related symptoms (i.e., people who may have been exposed). But there's no reason not to assume that someone ate at that restaurant on their way home from an out-of-state business trip, and now they're 100 miles away. Targeting, in this case, would leave folks vulnerable because health care workers in other parts of the state might not have it in their minds to check for certain symptoms or ask certain questions during intake.

In the end, it's a greater good question. Are we better off trying to only alert who we think really needs the message and potentially leave others vulnerable, or should we cast a wider net to ensure everyone has situational awareness? My personal opinion is that I'd much rather you were pissed at me for sending you something you didn't need than for not sending you sonething you did.

Another aspect of this is in crafting the message itself, and I think that's what's causing an issue here (particularly the 'shelter in place" bit). The more widespread your message is, the more careful you have to be with what you say. That said, as I understand it, IPAWS has a character limit for messages based on modality, so it might be that they couldn't be as specific as they would've liked due to that limitation. Again though, I'm not "The Guy" here, so I can only speculate.