It's unfortunate that this was the experience you had. I imagine whomever you talked to was under the impression that hardware can't be taken that isn't accepted as part of a Genius Bar appointment, and didn't know the severity of what could happen would the battery fail. A training failure on Apple's part. That said, my cousin took a similar era MacBook to the Apple Store for swelling, and was able to see a Genius that afternoon and got a battery swap.
Back in the day, I had a removable white polycarb macbook battery swell. Brought it in and they gave me a quick swap (no charge). I was pretty happy. I wonder how much the extra work dealing with internal batteries cost a company.
