You can sue for anything at all. I could sue you for failing to have an Internet connection. (Point being that there are no restrictions on what one can sue for, from the ridiculously pointless to the actually false.) Of course, it would be thrown out of court immediately, but I could still fill out the paperwork.

They do have something of a legitimate complaint in that people are implicitly telling folks that oranges will make them fat. It's not much of a complaint, but it's more than my example. I think they'd be better served by ignoring it, though.