There was a semi-intelligent discussion about it on FB. He's Cuban, in his mid-30s and didn't defect to the US until February 2016. Some reports say he doesn't speak English and the "slanted eye" gesture might have been a way to show his frustration with the Japanese player. Giving the guy some space, it does seem that he got to the US and was immediately thrust into the MLB world. Some training in cultural adaptations might have been appropriate when he, and others new to the country, arrive.
The harsh penalty, but not affecting the WS, seems fair. It might be a silver lining for MLB that they get to show their firmness with a player before black racists ruin that sport, too.