That article seems to oddly assume that in the Newtonian explanation, deflection of air is implied to only happen below the airfoil rather than above. At least

That article seems to oddly assume that in the Newtonian explanation, deflection of air is implied to only happen below the airfoil rather than above. At least when I explain lift that way, I gesture air being sent downwards both along the top and bottom of the airfoil. As to explaining why air above the airfoil has to go downwards it seems pretty obvious that the air gets sucked into the gap left by the airfoil, but more importantly the article left out the Kutta condition that air doesn't wrap around a sharp trailing edge. This is both an intuitive phenomenon and crucial to the estimation of lift.