I really like the idea of trying to solve an existing problem.
You forget your phone but how do you access a webpage in an emergency?
If this works for you and your personal use case, then everything is fine. But I see a lot of hurdles along the way here.
I would rather think of something like: If my phone hasen't been moved over an X amount of time (locations based or accelerometer) the phone drops a note to predfined receipients with "My phone hasen't moved in 60 minutes, maybe I forgot it somewhere". You can send a location point, but that is just where the phone is.
At least it would solve the point where you have to do something manually.