Ah but being vegetarian is more than just "no meat" versus "reasonable amounts" of meat. That is a common misconception of vegetarianism. I don't think she meant healthier as in solely a meat free diet, but maybe because she is making health conscious decisions all the way around, and a person that would be defensive might be eating meat that also happens to be unhealthy, like cheeseburgers and onion rings all day. That isn't a carnivorous statement, it would be nearly the same as BK veggie burgers and onion rings all day.
A lot of people just aren't concerned with what they eat, and a person that might be making health conscious decisions that also doesn't eat meat, might be a threat. Hmm, wait. Strike that. Thinking more of this it makes me think that somebody secure in their diet wouldn't be threatened, but if somebody knew they were consuming too many artery clogging foods (not particularly meat, but dairy products more likely) for example, and might be thinking they need to make some changes, assume that the vegetarian sharing the table could be acting condescending when they are not. (Although I'm sure there are veggie snobs out there too..) Some people assume that because a vegetarian promotes their way of eating that they might be saying that their way is better for everybody. I think the veggies are more on a defense overall, and the common event of explaining 'why' just comes out whether we've been asked or not because we are commonly stereotyped that being a vegetarian is only because 'no meat is healthier.'
And not all vegetarians eat a healthy diet. If somebody ate fettucine alfredo, fruit loops and grilled cheese sandwiches all day then they wouldn't be as threatening to some people.
Now, back to misconceptions about vegetarians. We aren't all just cutting out meat for health concerns. For many it is a total package. Cutting out meat that has hormones and antibiotics, eating more vegetables free of pesticides, finding low cholesterol alternatives, eating heart healthy protein sources, getting balanced fiber for heart and colon health, focusing on antioxidants, etc. Vegetarians stand to have a very unhealthy diet (see the alfredo comment above) if not more concerned about the whole picture. So it goes much deeper than meat for a lot of us.
Now, with all that said, you might think I'm implying I'm a health nut. Actually, I'm not a vegetarian because of health concerns, but because of animal rights and the way that animals are treated in a mass market of profit and greed. And then there is the effect that all the animal methane has on the ozone layer, but that is boring to anybody that isn't into that kind of research, so I'll spare you.

If I lived on a farm I might eat meat from animals that were given a proper life and able to move freely in a clean environment. But that IS another story, and I have to get my butt ready for work.
