(For context, I thought I was aro ace for a decade. I wrote a thing about that here if you're curious.)

First off, I don't believe in the split attraction model. The split attraction model isn't something that a researcher came up with to describe their findings, such as the Kinsey Scale. It's not a concept a philosopher put forth in an essay, complete with an explanation and defense. This framework is literally just something someone on the internet came up with, and then other people were like, "Sure, ok," and started using. The only evidence than posits this is a useful or accurate way to describe people's patterns of attraction is anecdotal accounts of "this works for me," and for each of those, there's more personal accounts saying the opposite.

I've yet to see a satisfying definition of romantic attraction in which it's not contingent on sexual attraction, but is also distinct from platonic fondness. I think romantic attraction is fondness (like friend fondness) but flavored by the hormones that attraction triggers. Sure, there are some people who aren't really interested in sex, but I see that as a variant rather than a distinct sexuality.

I do think that real asexual people (aromantic asexuals) do exist, albeit very rarely. It's the logical 4th sexuality: there are 2 sexes, each of which you can be into or not. And those real asexuals have a fair amount in common with gay people—lacking cross-sex attraction and being unable to be part of a straight relationship is a big deal, and to brush that off as "nothing" is very flippant.

But at present, I don't think it's logistically possible to include them without opening a huge can of worms and causing way more harm than its worth.