Re: A rules question!
He's asking what the rule is if he puts the marker down, picks up his ball, and goes back and notices that he somehow put the marker down so it was pointing way offline - can he go up and, without putting the ball back down, twist the marker so it's pointing more towards the general area in which he'd like to start the ball.
Furthermore, if you do move the ball marker in changing its rotation, is marking a point with your finger or a grain of sand sufficient - like marking the spot with the toe of your putter when you need to move the ball marker sideways?
However, a player can still claim:
a) that he had properly marked the position of the ball mark and was moving it (like you're allowed to do when asked to move your ball mark to the side of a player's intended putting line). He could do that with a small rock or a grain of sand, remember.
b) that he was attempting to rotate the ball mark or even to tap it down and it moved accidentally. Rotation isn't "movement."
In case b, you might suggest that the mere act of "touching" the mark, like touching the ball to rotate it without a mark, is enough to penalize you. I would say that it seems not to be, since you're allowed to touch the mark while brushing away loose impediments. The mark is not the same as the position of the ball, nor is it the same as the ball itself.
Note that the OP said he'd rotate the ball marker - not move it and rotate it. I think that may be a key difference (though in reality, like our inability to put the ball back "exactly" in the same spot, it may be an irrelevant difference too).
Try this one on for size: what if a guy goes to tap down his ball marker with his hands, but sneezes as he does so and knocks the ball marker away. Is that situation synonymous with the "sticks to your putter while tapping it down" Decision, or does it fall under the "sticks to your foot" type of Decision? I'd say the former. So then how is this rotating the ball marker when it doesn't even actually move (as defined) become more like the second type?
I think I've laid out my case... Frankly, I'm nearly 51/49 on the way this goes, and that slight difference is largely due to my understanding of equity. The guy's not trying to cheat here, and if he purposefully tries not to "move" the location of the spot he's marked, I think it's okay.