Bearing in mind Emirates would have their own staff at Newcastle, and probably more hotel accomodation than the area closebto Prestwick, if they had to put passengers up overnight..why would they divert to Prestwick ??
They don't self handle, they would be Swissport staff in uniform who may or may not be in a position to work on. What used to happen was passengers could be bussed from GLA to PIK but that's dependent on the roads being open of course. Also depends on PIK having fire cover on demand for a B77W.