Its assumptions are inconsistent with the conditions in the material world, but that doesn't make the model itself unsound. A model is not an argument, definitely not in the political sense, it's just a model.

You can also include the model in the material world, as was done, at the very least, when the paper introducing it was published and that doesn't make the material world unsound, either: The model lives in organic computation machines which implement paraconsistent logic in a way that does not, contrary to an assumption popular among those computation machines, make those paradoxes real in the material realm they're embedded in.

Everything is, ultimately, sound, because the universe, nay, cause and effect itself, does not just shatter willy-nilly. "ex falso quodlibet" would have rather interesting implications, physics-wise. For one, an infinite amount of Boltzmann brains would haunt an infinite amount of physicists.