I think we need a more appropriate definition of Math 0 that doesn't rely on the negation of some property such as "being actively bad at math".

It seems like what you really mean by Math 0, outside of that one section of the Bayes' Rule questionnaire, is "This requisite denotes people who have little to no mathematical skill outside of basic arithmetic and some problem solving," which is intuitively what makes sense for that level.

I think it's kind of unnecessary to state that Math 0 people are *not* averse to numeracy for whatever reason, to specifically block out the people who "hate" math. The Math 0/1/2/3 scale is supposed to be a sliding scale of ability to read mathematical notation and understand some baseline concepts; psychological aversion or active ignorance is another dimension altogether.

For example, somebody might be traumatized by Galois theory due to having an especially hard time learning it in courses, but they'd otherwise be fine learning about anything else. Maybe they were great at math as a kid but then something happened in their adulthood that started making them hate it. In such a case, they'd still be able to understand things, and it's that exact understanding that traumatizes them. Such a person might even be at a Math 2 level if they hadn't been traumatized, but this scale places them below Math 0 for an entirely unrelated reason.

It would be a better thing, in my opinion, for us to guide people like these towards resources that can help them get over that aversion, rather than excluding them from Math 0 and telling them to come back when they don't have that problem anymore.