This is wrong, for reference. The gaps in size between the levels of the Tiering System aren't inherently about "More real vs less real," so much as they're about there being an uncountably infinite difference in power (For a very informal definition of the term, of course) between Level X and Level Y, and we just so happen to equate ontological differences to that, as a lowball.
For a very extreme example showing why that needn't be the case, consider a space with uncountably infinite dimensions (Or with a cardinality larger than aleph-1, same difference): This space would obviously be Low 1-A or higher, and yet there is absolutely nothing that distinguishes it from ordinary 3-D space in terms of ontology. It's obviously not really any more "real" than the 3-D space is, just really, really, really, really, really big compared to it.
Anyway, this particularly bothersome thing left aside: I'll say I'm neutral with regards to whether or not "the space beyond" is Low 1-C. As I've expressed to some of the thread's participants off-site, I think this largely depends on whether we consider inherently finite visual representations (In this case, a universe being mistaken for a star when seen from the space beyond it) to mean anything when it comes to infinitely large objects and spaces. Although I will say that being finitely, or indeed even countably, larger than a 2-A space, is not a thing, no, unless the verse makes clear that such a thing is possible, in which case we're obviously forced to roll with it. As a default, though, we don't do that.