You are right.

But let's reduce it down to physicists working in quantum gravity, who publish in journals that such physicists typically publish in. Give that this is Sabine's background, this is who she will be aware of. For all that he's done, I'm pretty sure that Wolfram's works have not been published in such journals.

Roger Penrose is an even better example. His claims to be a physicist include a Nobel prize. But people working in quantum gravity dismiss his theories, so he doesn't publish in the right places, and so Sabine didn't think of him.

In short, Sabine is only likely to think of people in this context because their scientific work intersected hers.