Would You Take a Homemade Sandwich to a Restaurant?

So here's a frugal question... Someone I know, (I swear this story is not about me), has been brown bagging lunches in an effort to save money and eat a more balanced diet. One afternoon a bunch of coworkers asked if she'd like to go out to lunch with them. She considered the offer, but didn't really want to waste a perfectly good sandwich.

She knew the lunch she packed was healthier and cheaper than one she would buy, but she didn't want to eat alone while all her other coworkers went out together. After contemplating the options she decided to head out for lunch with her coworkers, but decided to bring her sandwich along for the ride.

When she got to the restaurant three of her coworkers purchased meals, while she purchased only a drink and chips. The four of them sat outside of the restaurant and ate their lunches at a picnic table.

After the incident a couple of coworkers commented that they would not have been comfortable taking homemade sandwiches to an establishment and one woman said she thought it was 'wrong to bring your own food.'

So here's my question... Do you think it is wrong to bring a homemade sandwich to a restaurant? The woman reasoned that she did purchase chips and a drink so she did not freeload on the restaurant and because her friends were eating at the same table she did not unnecessarily take up a seat. What do you think?