Does the dash have to be in to install windshield

The shop that did my body work seem to me to keep finding more to do before I bring the car home. I asked them to install the glass to keep it dry on the trip home. They say they have to install the dash first before the windshield. I need to do some work on the dash plus their work is extremely expensive. Are they being straight with me?
Yes, and no. Factory correct....they're telling you right, but, as 67dart273 stated, there are ways around it.