Mr. Hatfield is assuming that all PLers squat the same way; that is, with a lot of forward lean. As you can see in his article, under safety for the spine, that the more upright the lifter is the better...no matter what "sport" he or she is in. He also mentions that it is only dangerous for powerlifters who don't periodize. Meaning, we don't squat that way all the time, it's just that sometimes at maximal force, a little too much lean can happen, but we train to handle that (goodmornings). That's much different than people who go to the gym and crank out 3 x 15 like that week in and week out. I personally don't do full ROM 1 RM squats EVER, thus, I don't place a lot of shearing force on my spine. While he does a great job of highlighting the various squats seen, and their purpose, that doesn't mean that they are all best in terms of safety. Again, the fact that you aren't using maximal weight makes the undue stress on the knee seem ok. The good Dr. even warns toward the end that a BB squat is dangerous to lean forward in because the lower back has not been trained to handle it, and he mentions that doing them at high weight is a problem (restating what I said about getting by with it due to % of max). If a PL squat is guilty of being hard on the lumbar spine (which I disagree with-depends on the lifter) then a high bar squat is just as guilty of being "dangerous" on the cervical spine. He also says "slightly acute" knees. This is not the kind of danger I'm talking about. Sure, the more vertical the better, but I'm talking about those peple that just deliberately lean forward and move with the knees first. That's not the same things as descending straight down with the bar moving in a straight line over your ass, and the knees naturally coming forward a tad.
I don't think any two squatters in my gym squat alike, and we are all taught the same way.