Whether we live in a simulation or not is not a question that physics can answer. Unless it's a question of "are we living in a simulation that's running on a computer in a universe with exactly identical laws of physics to our own" which is much more boring. The paper's pretty cool, though.
All that said, the idea that we're living in a simulation is silly. It's on the same level as solipsism, saying that I'm the only one that's real, and that everyone else and the whole external world are just figments of my imagination. Both ideas are functionally useless, philosophically boring, and impossible to prove. And believing in either solipsism or simulation theory requires you to set such impossibly high standards of what it means to "know" something that it isn't actually possible to know with certainty that anything is true.