Do you think the reason J.K. Rowlings had Mundungus disapparate upon seeeing Voldemort was?

so that we could see him later on in the movie. If Mundungus had gotten killed or something, he would not have appeared later on the movie as he thief of the locket. I am wondering why Rowlings had Mundungus as the thief and not someone else given that she would have no reason to have Mundungus disapparate.