Those are fine, I don't see any twisting or forcing the back in any position beyond the normal range of motion. Except #6 , and I notice 1.) it's saved for last, and 2.) it's not anything too far out of the back's normal range and is not really forced.

Compare, if the person was standing, and asked to do a very deep hamstring stretch, that's where you start tearing stuff, IMO. The article mainly focuses on the harms of various twisting exercises, but it's very scholarly and well-written, and I would dare anyone to find anything in the article (as opposed to my clumsy summary) that is terribly debatable or unorthodox.