Whenever this particular issue comes up - with this player or others before him - I always take a moment and l remember what it feels like to actually intend to fault. Try it some time. Try and see if you can do it - no, not just plant that step through foot and then throw - but try and throw *right* at that moment, like you were *trying* to get away with something.
There is something jarring that happens if you actually plant that front foot before you let go - its a weird feeling, very disjointed. Granted a step through putt is a different feeling thing to begin with, but I had a hard time doing an intentional faulting putt with this style. Seemed my brain always let go before the other shoe got to the contact and to a weighted or supported point.
But then again at some point in basketball history, players brains could feel they were going to travel and tried to avoid it…
regardless, my own trials on seeing what it would take led me to believe that as much as our eyes may say one thing to us - I'd bet the true faulted putt using this style with a good operator is actually super rare.