If the ball is hit before low point, it will be inside out as you mention. However, if the ball is hit after low point then you will have Outside-in.
Not a 'news flash', nevercrosses. I've been preachin' that for thirty-one years. See 1-L #13 and #15.
Allow me to add a further component in the speaker's passionate argument: A divot. And not just any divot, mind you, but a divot carved Outside-In and to the left of the Target Line!
I'm comin', 'Lizabeth. I'm comin' to join you!
-- Fred Sanford
Sanford and Sons
Now what?
Are we to believe that, assuming a Square Plane Line and a Ball located Up Plane from Low Point, that a Clubhead moving Down an Inclined Plane through Impact to Low Point will take an Outside-In Divot?
Well, that's where, when and why I left 'De Plane'.
As I said in a post above, I now look forward to learning more about it, relating it to the principles that have served me well for three decades and drawing my own conclusions.