I'm going to take the other (unpopular) side on this one. For me it's very similar to the Allison Lee / Suzan Peterson debacle in the Solheim Cup a few years ago. In that case Lee picked her putt up before Peterson signaled to her it was good. Peterson got a lot of negative reaction for that and basically had to apologize.
IMO what Kuchar should've done is say to the official that he gave the putt to Sergio, but Sergio didn't hear him. To win on a technicality like that is not something I would want. Also similar to what happened to Annika in a Solheim Cup several years ago. Not a good look for golf IMO.