I may be misreading the post above but the way I am reading it, what is said is not correct.
When you replace a ball on the putting green it is "in play" the moment you let go of it irrespective of the ball marker being there.
So with the ball back on the ground, it is in play and you now remove the mark (itself an immovable obstruction). If you accidently bump the ball and it moves as a result of removing the mark, there is no penalty and you simply replace the ball.
If the ball is in play and at rest (hasn't moved for a second or two), if wind or water (NOT outside agencies) cause the ball to move, you play the ball without penalty from wherever it ends up. If the ball is blown into the hole, it's your lucky day. If it blows and rolls into a water hazard or OB, not so lucky.