Because of course Peter Pan being in a Bavarian village or medieval castle courtyard makes perfect sense in the "context of the park".
Once again, we see people imposing standards on Disney that it never actually has had. The theming has never been as rigid as some try to indicate and attractions/shops/restaurants don't form as cohesive a story as people suggest - why the heck are south pacific tiki birds next to African/Asian/South American river cruises next to Caribbean pirates from centuries ago?
Olaf is made of snow and enjoy summer. He's probably love to go to a place that had a blizzard but where water is melting to allow for swimming fun.