Sorry for taking so long to get back to you. It takes more than just one filter to build a custom location rule and you can just tack your taxonomies onto the post category rule.
Building a complete set of location rule filters, with the exception of “Rule Operators” is the only way to do this in ACF.
I have several examples of custom location rules, but none of them are for this specific purpose, but can be used as a reference. https://github.com/Hube2/acf-filters-and-functions
