I think their point is belief versus theory. One requires faith, the other thought.

It's why it's simulation theory and not Simulationism. People acknowledge it, but don't follow it, nor believe it, since belief requires clearing unknown gaps with leaps of faith to reach an unknown destination. Theory seeks answers of the unknown with "could be this, could not be this" whereas belief is "it be this".

This always points back to the paradox which all divinity falls into. The moment we know of a god to be real, it is old news and no longer divine. The next scientific step is "What made it so?" and moves right along to bigger things whether theists are on board or not.

Of the few words ending with -ism and -ist in science or theory, none have belief or faith.

Even the most apparent, such as the Big Bang Theory, are still marked a theory, after all. Believing in them—convinction without 100% knowledge—is foolish and closes doors of what may actually be truth.