The cases presented here have not relied on familial DNA for warrants
In the Golden State Killer case I heard the cop explicitly state that that wasn't enough to get a warrant. They went about getting the DNA through the unorthodox path of waiting for the guy to leave some DNA somewhere, i.e. litter.
One reason I don't have a lot of concern about this is that DNA is solid evidence. It's not circumstantial or eye witness testimony. It's difficult to get DNA wrong.