If we look at what law says ...
The following must be considered:
• distance between the offence and the goal - definitely ticks this, he is much closer to goal than he is the half way line
• general direction of the play - charging straight toward goal so this one is ticked
• likelihood of keeping or gaining control of the ball - has the ball fully under control, so again, ticked
• location and number of defenders - Kompany is obviously out of the equation, so that just leaves Stones. Vardy has a head start on him, and whilst Stones is no slouch, there is no way he would or could catch him. The only other player in picture, which I assume is Delph, has even less chance of catching him.
All four requirements fully ticked, there is no doubt at all it should have been a red card. I suspect it actually would have been had it not happened so early in the game.