Another angle is this......not only was said conveyance not in a place where the statute authorizes the cop to issue a citation, how did he determine the parking brake wasnt set??? Did he enter the conveyance and perform an illegal search without your dad's consent??

Another question....was said conveyance located on private property?
So we may possibly have misapplication of statute, trespassing, AND breaking in and entering here!!! Without knowing the situation better, I dont see how the cop can on good faith claim he had probable cause to issue a citation.
Depending on the situation, dear old dad might not only motion to quash the summons, he might also be able to make life not so nice for the nice officer! LOL