Well I think that particular petfood company might need to have a chat to their marketing team. Not all rottweilers play nice in public.
I think partially it should be the dog owners responsibility not to bring a dog that is not stranger friendly into an environment like a huge pet retailer.
However, dangling a carrot like free petfood (and I bet it's not cheap either) of course will mean people won't be thinking rationally. "I'll just take my agressive un-socialised dog in, get the food and leave"
What a shame too, I love Rottweilers they're absolutely lovely dogs.