[Symmetry]

The effective intensity of a laser falls of as the range squared, so you need a pretty hefty laser to dazzle someone at range. The intensity of reflected laser light falls of with the fourth power of the range, making reflected light not much of a concern for the crew. Its quite possible for the pirates to put a mirror between them and the ship, indeed it should be quite possible for the pirates to just turn their heads away from the defending ship.

The problem for the pirates is that its hard to effectively attack something you can't look at, however. Red glasses might be an effective countermeasure, though, as other people have pointed out.

[teaspoon]

If the mirror is wider than the cone of the laser (1 meter in this case), then irradiance still falls off as the range squared. Reflecting the laser back at its source only doubles the range.