Thanks for the response chaps,
All of what you've said definitely makes sense, increased weight due to tankering would lead to greater braking force required which could increase the risk of skidding on a contaminated runway, depending on weather conditions of course.
Unfortunately the brief didn't make it terribly clear if the fuel has been tankered prior to arriving at Munich or once the aircraft has landed.
Not sure if I'm completely shooting in the dark here but can some airport/handling agents choose not to refuel in cold weather (I know during thunderstorms refuelling isn't really an option)?