The back button in my browser is broken on this site. I know it doesn't matter for the product itself, but it's one of these little annoying things that leave me with slightly negative - instead of totally neutral - impression.
That still doesn't explain why they didn't just put the temporary page at /offers, though. I tend to give Google benefit of doubt and assume they had a sound technical reason when they do something I don't understand, but I'd like to see an explanation of the thinking behind that.