Quitting apps may be common, but quitting them because it’s the only way to dismiss a stuck notification is not. It is also inconsistent with the behavior of MDP’s other notifications, which display for a few moments and then disappear.
In contrast, this particular warning remains indefinitely and obscures the rest of the UI. It even persists between loading different layouts. The *only* way to get rid of it is to close the app, which should not be a common action to dismiss popups.