I don't think that's the intended use at all.
I'm guessing they're expecting texts more like "someone broke into my house, and I'm hiding in the closet", or "my husband is abusing me, and thinks I'm just cleaning up in the bathroom, but I need help", etc. Situations where being discreet is important, situations where people currently try to text 911, and often get no response.
Agreed. I don't think it's intended to replace a 911 call, but to provide an alternative in situtations, such as you provided, when a 911 call might not be practical. Another example would be during a mass casualty event where 911 calls can't get through because the towers are saturated. SMS messages use essentially no bandwidth and would be able to get through, providing emergency services and first responders with additional information about injuries, people who are trapped, etc.