Thus, we see that local causality condition (1) is mathematically equivalent to the assumption of joint probabilities, $p(A_1,A_2,B_1,B_2)$. The latter is a form of realism: complementary observables are treated as mere numbers [...].
This quote is taken from "Quantum non-locality - it ain't necessarily so" by Zukowski and Brukner. In this paper they primarily argue (as far as I understood) that the assumptions "locality" (in terms of factorizability) and "realism" (in the form depicted in the quote above) in Bell's Theorem are on equal footing [In contrast to views described in papers such as this one written by Norsen]. My question concerns the following scenario: If one adopts the view that both assumptions ("reality" and "locality") are indeed on equal footing, and then one decides to reject "realism"(existence of the joint probability $p(A_1,A_2,B_1,B_2)$) in order to restore locality - does this really suffice to rule out all possible forms of realism?
The existence of $p(A_1,A_2,B_1,B_2)$ requires that the possible measurement values exist, no matter which observables are measured on either side and more importantly the values exist prior to the measurements. But I can imagine that other forms of realism, e.g. nonlocal real hidden variables, do not require the existence of this joint probability $p(A_1,A_2,B_1,B_2)$, since the values of system $B$ can change depending on what outcomes are obtained on $A$ and vice versa. Additionally I wonder if another way of bypassing Zukowski's reality condition would be contextual hidden variables (since joint probabilites such as $p(A_1,A_2,B_1,B_2)$ look like a noncontextual state assignment, which is ruled out by the Kochen-Specker-Theorem anyway.)
I do not doubt the derived equality between their notions of "locality" (factorization condition) and "realism" (existence of joint probability) in Zukowski's and Brukner's paper cited above, but I'm certainly unsure if rejecting this "form of realism" would rule out all forms of hidden variables. I'm aware that this is a quite subtle topic, but nevertheless I hope I could convey my issue - can anyone help to clarify?