I would say it would be fine. We have a waterbed that sounds like what your father has. It has a pillow top that unzippers off all the way around, to reveal a bunch of tubes running top to bottom. Inside the tubes there is water of course, but there is often either large (5 inch maybe) plastic coil like springs or foam. This is supposed to add support and reduce the movement of water. Simply having the water in separate tubes as opposed to one single bag is like night and day. The most fabulous thing is that when dh does a triple lutz in his sleep, it doesn't wake me up.
Also with these beds, it looks like a regular mattress, uses regular sheets and doesn't need a heater because it is inside a reg mattress. It is safer for babe because it is firmer, and unlike regular water beds, it is NOT inside a wooden box frame. From what I understand, one of the big dangers of regular waterbeds is that babe can fall down between the waterbed frame and the bag of water.