[Someone1234]

There are fall sensors the elderly can wear, they often have a bonus panic button too.

In answer to your question: This isn't useful for anything yet as it is early academic research that mostly just proves it is possible, it would have to be refined and minimized to become commercially useful.

That being said I cannot imagine this being more accurate or cheaper than optical sensors + computer vision, privacy issues can be mitigated by building a closed-look with no outside connection. The point of this laser technique is for situations where you cannot/don't want to have direct vision of the location (e.g. inside the body, inside a room, etc).