I was hit by a lot of orbital strikes as a deployed repair sunderer on the rock bridge from Ti Alloys to Crown and I didn't move or blow up. I'm not sure if the portable skyshield had anything to do with it but it doesn't make Orbital Strikes worth calling anymore. It was good the way it was before. People were taking refuge inside the sunderer and no one died.
OS was never able to kill Sunderer - it leaves them burning. Also Anchored vehicles (deployed Sunderers, Prowlers, MAXes) are immune to physic impulses. Working as intended.