I have no idea what you're trying to say. Why would it be bad? It makes no sense. All it means is insisting it is true without evidence makes no sense. But nobody here is making that claim.
Unjustifiability means unfathomability; unfathomability suggests impossibility. And if simulation theory is impossible, its unfalsifiability is of no help.
This makes no sense to me whatsoever. You're using these words to means things entirely different from how I use them. Going by your use of them, simulation theory can not be proven unjustifiable, because that would make it falsifiable.
I don't have a rigorous proof that unfathomability implies impossibility, it's just a strong suggestion and demonstration that you incur a high risk of assuming an impossible thing into existence.