I think you have to look at the reason the fella knocked the ball back.....and that reason was because he wrongly thought he'd already won the hole, so I wouldn't say he gave the putt.
I think the fella needs to be notified of his mistake, it could have resulted in a 2 shot swing, and maybe a different final result.
I think the fella needs to be notified of his mistake, it could have resulted in a 2 shot swing, and maybe a different final result.