I can see why it was an offensive comment. He's trying to tell you that you don't know anything about running a resturant because of your job position, which doesn't make sense if say 99% of people knew how to stack a shelf theorically but didn't actually KNOW how to do it because they don't do it as a job.

I also think that the discussion was handled wrong. Instead of dismissing his opinion because you know your family don't have an issue with the take away boxes, agree with him but also comment that your family seem to cope with doing it without suffering so much. You can still talk about how it either encourages more customers, or that it can encourage losses by letting customers take tonnes of free food, and each of your opinions would have been respected.

I've learnt that men like to know stuff. My dad rarely talks about a topic on a chat show or gossip that is outrageous or deep feeling- unlike my mum or sisters. He's more likely to show me a new gadget he has, or a video that's funny- yes, just cos men can seem tactless when it comes to emotions, doesn't mean they don't have humour!- or crazy videos of incredible special effects or 10 feet of snow in Russia or the like. So if a guy makes digs at you in an argument, it's more likely he's trying to sound the most knowledgeable on the subject, rather than personally attacking you.

Glad you sorted it out tho. I don't think I'm mature enough to cope with men even when I'm thinking sensibly.