I dont think diverts make much money, all that is in it for the airport authority is the commission on the handling, fuel uplift and the departure / landing fee. The PAX if offloaded will be whisked straight through the terminal and wont spend any money. I would suggest deicing vacant stands properly to accommodate them would burn up that income.
So in these conditions its probably more cost effective to turn the diverts away. Remember the fiasco with the KLM MD11 a couple of weeks back ? multiply that by say 10 diverts and you have a god almighty mess that the Airport
PR people would prefer to avoid. So in my opinion probably more trouble than they are worth.