Not that big of deal. Clean it up, tape it up, put some rust inhibitor on, and paint it with a white rattle can. Do this every year for that matter. It is a 15 years old with how many, maybe over 100K miles. Rust on the windshield will not make it unsafe to drive in the winter. Now if your frame is rusted thru that is a different story.
You could paint your wiper arms with a black rattle can too...that would make it look new!!