Rainboe is spot on (again!)
greuzi
For a rare event like this it therefore makes sense to keep the global network moving and keep airframes, crews and passengers where they should be in the world. Cost here is expensive for sure, but putting up a few B747, A330, B777, A340 full of stranded pax in nice hotels is not cheap....
The problem there is that the infrastructure cost is BAA in outlay and then to reclaim. If they close the place - the bulk of the costs hit the carriers. Of course, BAA lose handling fees and other stuff but they do not have to pay for pax/crew hotac
nor the problem of a/c being in the wrong place and causing problems over the next week as they catch up. (I sit to be corrected)