Main issue with a dyson laser is that no one would actually use it.
Density of solar energy drops (duh) with the square of distance from the sun. This equals to the amount of hardware you need to build, deploy, and protect also increasing with the square of the distance. So if you want to do something with sunlight you always want to be on the inside not outside.
I think the hypothetical planet killers would build a fleet solar powered lasers large enough to hit a planet from interplanetary distance, deploy them inside the orbit of mercury, and then have fun shooting down anyone trying to destroy them. Lasers being quite a bit better at shooting spaceships or missiles than huge mirrors are. And much smaller targets.
So while a civilization capable of building a dyson sphere probably could build a dyson laser, they also easily could get the same effect with an order of magnitude lower use of resources and time.
And wasting an order of magnitude of your resources is not really feasible to do from the viewpoint of economics or politics. So I guess the answer would be no.