And I'll take the opposite point of view
I would think that by swinging in the rough to
intentionally (<--- and that's the key) junk up the grooves would be a breach.
To me, it's about the intent. It's like when you're trying to hit the ball, and whiff. Your playing partners can speculate as to whether it was practice or real, but you should add a stroke, as you swung with the
intent of hitting the ball.
It's similar, IMO, to when you hit your ball with your practice swing. No intent to hit it = no penalty (oddly enough).
So, to me, yes - if you take practice cuts with the intent of crudding up your grooves to make less spin, you're in violation. The second paragraph of the decision: "The most important question to ask when ruling on a club which has had something temporarily applied to the face by a player is ‘why has it been put there?’ If a material or substance has been applied to the face in order to protect it (e.g., to increase wear resistance) or to clean it, then it would probably be permitted. However, if the purpose of the application is to influence the movement of the ball or assist the player in making a stroke, it would be prohibited." seems to support this view.