Assuming both tires are at the same pressure and both tires have the same carcass stiffness, the size of the contact patches in a 50/50 weight distribution scenario must by definition be equal.
What will differ is the shape of the contact patch.
But to answer your question, take a look at your typical low side crash during a MotoGP race. What's happening there? Answer: The rider is trail-braking too deep into the corner and exceeding the traction limits of the front tire, thereby "tucking" it. Too much lean plus too much load (i.e. deceleration) and the tire gives up. Increasing the size of the contact patch by loading the front does not give you unlimited grip.
Take a look: Valentino is still leaned over a bit and in the last part of their turn when the front wheel comes off the ground under acceleration.
So there's more going on here than having the front in contact with the ground throughout the turn.
