I used that app and it worked fine. In the thread the people that bricked their phones were the ones that used the app to re-enable knox. He took that option out of the 1.1 app so it's disable only. I used the app to disable it, but in android tuner it says the notifier app is just frozen. If I wanted to re-enable it (which I see no reason to) I'd just unfreeze it.
You can also use titanium or android tuner or your favorite app to freeze the notifier with the same results.
Or you can just tell it not to warn you for another 30 days and then flash the new .tar when its released.
I soft bricked my phone about 4 times already and restored it using twrp and my backup. As long as you're using the latest version it works fine. I wouldn't advise playing around until you know you have a backup that works though. If for nothing else but to have peace of mind and to not have to start over with odin.
Wife walks in...
Wife: Hey what are you doing?
me: Nada, phones finally rootable.