Doesn't have to be intent to hurt (which is not supported in the law), doesn't even have to be hard. FIFA's view is basically that because there's no good reason to do it, that immediately upgrades it to 'excessive'.
Could it be argued from a players perspective there was good reason to do it, therefore its not a red? This is definitely not black and white. I can see both sides and a very tough decision it would be in real time.