The Department of Justice in the territory issued a statement saying: “Grace Mugabe is not liable to arrest or detention, and enjoys immunity from prosecution.” These rights come under Chinese regulations on diplomatic immunity and privileges, the department said.Very well then, following form then consider for a moment that the P.R. Chinese make no mention of "conduct incompatible with diplomatic status". Either they applaud foreign "diplomatic personnel" slugging representatives of the local media, or there is a double standard being applied. That might not matter within the mainland, but if the matter came before Hong Kong courts, it might just be arguable. Maybe.
Far better, but highly unlikely, would be for Hong Kong to revoke any permission for her to enter the region.