I will believe it when I see it. Focusing that much light on a small moving object, through layered and moving air, with an intensity to burn through metal would be an achievement. Burning through enough of that metal to degrade a falling rocket (as opposed to during boost phase of flight) is even harder. For all the talk about cost reduction, have a look at what realworld laser armor costs. Painting the nosecone of a rocket white, or coating it with reflective foil costs next to nothing but is remarkably effective.
Better question: What would this do to a manned aircraft? There is a reason there are treaties against blinding weapons.
Better question: What would this do to a manned aircraft? There is a reason there are treaties against blinding weapons.