In theory, yes. In practice, this just doesn't happen. How many times has a referee been to the monitor and not reversed his decision? I can't remember a single one.
It's as if the VAR is the senior referee and if he says go to the monitor, you know you have made a mistake and are instructed to change your decision. It's almost like a protocol.
In hindsight, I think Dean was right not to refer Taylor to the monitor last week because that would have resulted in Taylor changing his mind and sending the Spurs player off - because that appears to be the protocol. However, Dean will have seen Taylor looking straight at the incident. He knows Taylor can't claim to have missed the incident, so it wasn't right to ask Taylor to go to the monitor because Taylor deemed the incident not worthy of punishment for violent conduct. That is a subjective decision about which two referees are entitled to hold differing views.
The Trippier incident today is the same in my opinion. The referee deemed it a red card, having had a clear view of the incident. His view wasn't impeded. There was nothing extra in the review that he didn't know without the review. It wasn't a clear and obvious error - just a matter of opinion. It's fair for other people including the VAR to have a different opinion, but it is a subjective matter, so the referee's immediate opinion was not wrong or invalid.
VAR should be correcting errors, not overturning decisions based on subjective interpretation.
FIFA's definition of violent conduct is "Violent conduct is when a player uses or attempts to use excessive force or brutality against an opponent when not challenging for the ball."
Trippier was not challenging for the ball. The question is, did he use excessive force or brutality. I think he did. The referee thought he did. These are perfectly valid opinions, and the referee having this opinion is not an error. The VAR thought he didn't use excessive force or brutality. A valid opinion, but having opposing opinions is not an error.