Agree with first part.
And you're right, the fact that they told him to take a second look already means the ref has gone from guilty of a foul to maybe 75% guilty of a red card without looking at the screen.
Someone standing with a knife in their hand and a body on the floor, guilty or not? That's the argument. The fact that the screen showed the bent ankle must have been an influence on the ref as he walked up to the screen. Had the screen been blank and just shown the foul, either normal or slow...
If this wasn't football and it went to court, the defending lawyers would have a field day saying how VAR 'left the image of a bent ankle' up on the screen as the ref walked towards it. This alone probably changed his mind.