The pilots are complaining. Listen.
They are the ones affected, and they know how much it affects them. If they say it's unsafe, I will not argue with them.
People have instinctive reactions to bright lights shining in their eyes when they are trying to concentrate on something. They may move to the side, they may close their eyes, they may block the light with their hands, whatever. The point is, that at best they are no longer concentrating on what they should be, they are concentrating on avoiding the light.
What if they shined a laser into your eyes while you were driving on a motorway? If a few drivers (but not all) complained, that should be enough for the practice to be banned and prosecuted.
And speaking of prosecution, the culprits should at least be forced to pay for the fuel used in a go-around, and the mainenance on the extra flight time. Then some kind of hourly wage for the passengers.
For second offenses, after they have paid up again, have them drive at speed on a racetrack and shine a laser into their eyes at every turn...