If somebody is willing to buy a meal....why deny it?
A lot of air carriers don't have catering service set up at certain airports, or for certain flights. Hot meal service is set up in advance. Let's say they sold a meal to the woman, but a 1st class passenger on the next leg wasn't able to get a hot meal as a result.
Logistics in commercial air service can be a nightmare. It's not like they can pull through a drive through for a hot meal. Most people don't ever consider these issues, because they don't understand anything about the service they use at the mere click of a mouse.