No. In a conversation with the Dapple-Gray about the detestable
Yahoos, Gulliver suggests that the Houyhnhnms exterminate the
Yahoos through the benevolent use of castration. The Dapple-Gray
then brought the idea before the Grand Assembly.
Yes, the Dapple-Gray did suggest castration, but it was
originally Gulliver's idea (from his experience with horses in
England) and it was suggested as a means for annihilating the
Yahoos. They would castrate the Yahoos and let them slowly die out,
thus exterminating them.