Much as I despise using Wikipedia as a source, the last paragraph on the decision is of interest here. In later years, the decision, though not overruled, was narrowed.
On December 27, 2012, the Supreme Court of California reaffirmed Pruneyard but narrowed its applicability to the facts of the original case.[18] The entire court concurred in Associate Justice Joyce Kennard’s holding that Pruneyard applies only to “common areas” of shopping centers that are designed and furnished to encourage shoppers to linger, congregate, relax, or converse at leisure, but does not apply to any other open portions of shopping centers merely intended to facilitate the efficient movement of shoppers in and out of tenants, including concrete aprons and sidewalks which shoppers simply walk across as they move between parking lots and big-box stores. In other words, the court effectively immunized most (but not all) strip malls and shopping centers from Pruneyard, except for those with areas analogous to public gathering areas such as plazas, atriums, or food courts. Miriam Vogel, a former Court of Appeal justice who argued for the shopping center tenant (Kroger subsidiary Ralphs), characterized the decision “a great victory for retailers as far as putting another nail in the Pruneyard coffin.”[19] However, the decision was not a complete loss for free speech advocates, as the court separately upheld the right of a union to protest on the employer’s premises under the state Moscone Act by a 6–1 majority (the majority, though, was badly split as to why).