As was communicated till now, upgrade users will have access after the finalized modules are released, i.e. out of beta.
I'd assume that for some reason it would take a disproportionate effort to have both BS2 versions in beta or rather keep releasing different patches as the beta goes on.
As ED has limited ressources we wouldn't want them to waste time on that which could better be used on the next DCS module would we? :D