That is entirely fair. And per @animats comment it isn't clear they have managed to do anything "new" yet.
That said, microwaves (like lasers) do tend to go straight. So from the point they start using them going forward, I would expect it to be possible (not easy, but possible) to keep them in a straight path.
> That said, microwaves (like lasers) do tend to go straight.
Actually, none of them do. Cutting equipment (even after adapted to drilling) is heavily focused on the near region, usually a few cm away. On distances larger than a few cm, they are no more self-aligning than any mechanical drill.
That said, microwaves (like lasers) do tend to go straight. So from the point they start using them going forward, I would expect it to be possible (not easy, but possible) to keep them in a straight path.