This seems unnecessarily dickish to me: It's a) a legitimate concern, and b) it's condescending. If the management thinks vegetarians are hippie idiots then don't serve vegetarian stuff. But insulting your clientele is not usually a great move.

The only place this kind of thing is even kind of acceptable (IMHO) is at like a BBQ place that prides itself on meat and meat-eating culture. "You want vegetables, we sometimes put parsley on the side of the plate. Yeehaw!" or something similar. That's ok, it's part of the image they're trying to create. And vegetarians will probably avoid it anyway (sometimes to the sad resignation of their meat-eating friends... I know this from experience).

Also, one other thing: For a place of business, this seems like a really self-defeating sign. It's not true, obviously (or at least I assume it's not. All available evidence points to not). But then what is the truth? Is it "We'll cook our anything we want wherever we want" sarcasm or is it a gentle ribbing about their separate cooker they have to have? Or what? If I was vegetarian and saw that sign I'd be annoyed at the condescending tone (unless it was one of the above meat-centered places) and would feel like I'd have to ask what the deal actually was, which completely negates the effectiveness of the sign.

I don't know, the whole thing is just blowing my mind as I sit here.