The counterargument would be simple: a counterexample where all three propositions are false at the same time.
The Simulation Argument is really a tool, and a challenge. It sets things up such that, if we manage to disprove 1 and 2 empirically, we get stuck with a shocking realization about the basic facts of our existence. It gives us an unusual way of indirectly testing whether or not we are living in a simulation. That's a lot out of something that "isn't an argument at all".
> The Simulation Argument is really a tool, and a challenge.
No it isn't. It is Pascal's Wager updated for the 21st century. The only way it can be "proved" is if we are living in a really bad, poorly maintained, fundamentally broken, cheaply outsourced simulation.
The Simulation Argument is really a tool, and a challenge. It sets things up such that, if we manage to disprove 1 and 2 empirically, we get stuck with a shocking realization about the basic facts of our existence. It gives us an unusual way of indirectly testing whether or not we are living in a simulation. That's a lot out of something that "isn't an argument at all".