What they're saying is that if the wing is horizontal, it will produce very little lift, as it will only be in relation to the falling of the rocket. In other words - if you want to fly horizontally, you need to have the rocket up at an angle right now, whereas with improved physics you would be able to have lift with only pure, horizontal thrust pushing the craft forward. Also, wings (if they use the generic airfoil shape and not a symmetrical one) should only generate lift in one direction unless at negative AoA's exceeding like 5-10 degrees.