It's bizarre - you're describing the reasons why it wasn't simulation, then saying it was at the end with your final sentence!
It is what it is - Vardy has came together with the defender, they've clashed, no foul, no dive, play goes on.
He has tried to cheat to win a penalty. No one wants this in the game as other refs would have given the pen. So he was rightly booked and then sent off for it.