> Let's make it disappear after a little while, this way it won't repaint when the app is loading. So a delay of 1 sec should be good here

That instruction doesn't remove the effect, it prevents what the blurring effect appears if the time between touchstart and touchend is less than 140ms (quick tap).

> Then you can also reset the state when the visibility of the app is set to true (in the case the user hit the home button quickly).

It makes sense for sure. If the tap is slow, the blurring effect appears and when the homescreen gets hidden (visibilitychange event) it will disappear.