What justification did Reldresal present for blinding Gulliver?

From the text:

That the loss of your eyes would be no impediment to your bodily strength, by which you might still be useful to his majesty; that blindness is an addition to courage, by concealing dangers from us; that the fear you had for your eyes, was the greatest difficulty in bringing over the enemy’s fleet, and it would be sufficient for you to see by the eyes of the ministers, since the greatest princes do no more.