Just so I'm sure I've got all this... By RuleTM, 1) Roughing the Kicker can be called whenever a player kicks the ball, 2) Roughing the Holder can be called whenever a player holds the ball, 3) Roughing the Snapper can only be called based on the actions/position of the Kicker and (optionally) Holder?
In reality, a) I doubt any R linebacker will see the holder pick his knee up and realize he's allowed to charge into the snapper and b) if he does, it could still be a personal foul for unnecessary roughness.
Worse still, team comes out for the try, holder puts the block down and then sees the condition of the field -- "Ew, that's muddy... I don't want to put my knee in that..."