Of course your Dad should use the tent he prefers, but he would have no problem camping on solid rock with a non-freestanding tent. I have done that many times with my Squall 2 from Tarptent. I have loops of light braided dacron fishing line at the place there tent stakes go. These are 150 lb test, and very light. If I can't get a stake in ground, I put a rock in the loop, and scootch it out till the tent is taut. Tenting on solid rock is no problem with a good inflatable sleeping pad, and I've always been able to find rocks or logs for the 6 stakes needed for the Squall 2.
