But you only get one try. 15/16 times you get a very visible failure.
It isn't great. Most users won't assume malice when an app crashes. And if they reopen it a few times your chance of succeeding goes up quickly. But this is also assuming that you need a single pointer tag to exploit something. If you need more you need to get even luckier.
So it definitely isn't perfect protection. But it isn't trivial to bypass.