I think Rossi doesn't want all his fanbois to jump ship and support MM after he retires. This way MM is now the villain and Rossi's minions will forever see MM this way.
The smack VR spoke earier in the week. He knew exactly what was going to happen. This way he loses the champ and says "I lost cause of MM". If this didn't happen he would have to say JL was the better rider.

And for sure you can see his leg kick. What a dog.