ARRGGHH!
You mean he didn't put up a plastic drop cloth to seal the rest of the house from the dust???

We found out that using a shop vac while doing the sawing is a great help.

I'd ask him about both of those things!
Or ask him if he is doing ALL the clean up when he is done.

If he won't maybe tell him you'll get the stuff to do it and subtract the cost from his bill..

If all else fails - get sheets and plastic and cover as much as you can.