Frankly, the job of law enforcement is up to people in law enforcement. We're not responsible for them. Their physical inability to do certain kinds of harm is part of the balance between civil rights and law enforcement.
Most people who benefit from Burner won't be criminals. It'll probably end up reducing crime by protecting potential victims. Most people are good, so when this thing is doing it's job, it's mostly going to be protecting good people. The additional safety will encourage people to have a better feeling of safety in their lives, as they'll be taking smaller risks when using their phone and interacting with other people. In single life, this thing is frankly a godsend, and can really make a substantive improvement in many peoples lives... Especially for those who've previously been victims.
Worrying about whether to protect people, versus easing the jobs of the people who protect people, is absurdly myopic.