He tripped him, not kicked him. It was a so-called professional foul to stop Zab getting in behind him. The FA panel decided it wouldn't have warranted a red card and (regretfully) that's probably the right decision.
So tripping someone, does not involve actually kicking them & doing so whilst they are running at decent speed, with no knowlegde of the assailant's intentions, does not involve the risk of causing injury as they fly arse over tit & their shoulders/neck hit the floor, so is not at all 'violent conduct' as opposed to say, pushing your head forward at about 0.001 mph, like in the case of Nolito's red card, which of course could have seriously injured his opponent & is therefore 'violent conduct'.
I know which I'd prefer.
It's a load of fucking bullshit, with no consistency, interpreted by fucking idiots & adjudicated by Sky TV.
There is absolutely no way, Nolito's action is worse than Puncheon's, & both are 'off the ball'.
If the same action was done as a retaliation, it would immediately be a red card. Either both are reds, or neither are reds.
Utterly ridiculous state of affairs.