1. Wait, what happens if the thief closes the macbook first? 2. Even if it works, wouldn't this be useless since the thief would not know about the app running

1. Wait, what happens if the thief closes the macbook first? 2. Even if it works, wouldn't this be useless since the thief would not know about the app running? Ie most theft prevention mechanisms works because they manifestly inform the potential thief that it's not worth his trouble to bother with this one. But if this is just an app running in the background - there is no 'warning' shown.