As other posters note, this is the crux of any argument -- we can all see how deliberate, petty and malicious this kick was.
If the ref didn't see it all properly, it explains why there was only a yellow card and any PROPER Compliance Officer (who actually knows about playing football) would upgrade that to a red card.
If the ref did see it properly, then he must be censured for ONLY dishing out a yellow.
And that PROPER CO must still upgrade it to a red, effectively stating that the ref has colluded with the player by providing a lesser punishment.
It all comes down to the question we keep asking these match and compliance officials -- are you incompetent, or just plain corrupt ?