Not only that, if you die after mating how can his mother talk to him?
(Edit) She's not his genetic mother. Note how the woman said "if you want your parents to roll over in their graves." She's the third person refered to in "That's Lobstertainment" who raised Zoidberg.
This drives home the point that not all of Zoidberg's species mate at the Frenzy. Some choose to live on to raise the children spawned from it and teach them the ways of their civilization.