Why would a cop go where it has become crystal clear over the years they are not wanted. In return, why would a cop respond to a call at a place that they are not wanted.
I don't know anything about Riverside County, but I should think it has other places that serve better, less expensive coffee and which would be happy to serve members of law enforcement.
I'd like to see what will happen the next time a Starbucks is robbed or some other crime is committed in one of its establishments. Stories like these get around to every other law enforcement agency and the police may be reluctant to respond to the next 911 call from a Starbucks.