MLB needs to retrain their umps, then. Two sets of them got the call wrong.
I would need to read the rule. Didn't look like anything nefarious to me but since I don't know the official rule...there is a difference between being illegal and dirty so I suppose it could be breaking the rule but not with intent to injure.
From what I understand this is what happened and the umpires missed it.
League-wide there seems to be confusion regarding the interpretation of the rule. Officially, the runner's deviation from the baseline to disrupt the play is considered to be interference. So while perhaps it wasn't a "dirty" play with the intent to injure the catcher (e.g., sliding spikes up), it was technically an illegal slide.