Milk & Meat

Question

My son asked me whether he could work as delivery person for non-Kosher Pizzeria. My initial response was to say 'No' because of the prohibition of benefitting from the mixture of dairy and meat (eg, earning an income from the delivery of a pepperoni pizza). Then I thought about it and wondered that this extended logic could apply to even a supermarket cashier earning a wage checking out similar products. so I thought I should ask you. 1) Can he work delivering non-Kosher Pizzas (not making them)? 2) By extension, Could he also wait tables in non-kosher restaurants? Thank you!