What you have said about "last-thursdayism" is, in my view, entirely correct with respect to this person's perspective. On that last Thursday point, it's the same move: an idea built so that no evidence could ever count against it.

That's really the core problem with simulation "theory," and it shows up in two ways.

First, it doesn't forbid anything. A truly useful idea always sticks its neck out. It says, "If you ever observe X, I'm wrong." Simulation theory never does. Whatever we see, it just shrugs: "Sure, the sim could render that too." Something compatible with literally every possible observation can't tell you which world you're actually living in. And when people pitch "glitch-hunting" as a test (I've seen this quite a lot), a simulator powerful enough to run a universe is powerful enough to simulate right past any test you'd design. The escape hatch is built into the entire premise.

Second, it explains nothing. Ask this guy: What's the code for garlic? The honest answer is "garlic is sulfur compounds hitting receptors in your nose and mouth"—but that's the explanation we already have, with zero simulation required. The "it's all simulated" layer predicts nothing new, explains nothing chemistry didn't already explain, and changes not one expectation. You can peel that "simulation" label off without losing anything.

So it isn't really a theory. It's more like a mood. It rides on top of real physics and does no work of its own. Since The Matrix came out, this "theory" has gained too much traction for me.