Do not consider Collectivists as "sincere but deluded idealists". The proposal to enslave some men for the sake of others is not an ideal; brutality is not "idealistic," no matter what its purpose. Do not ever say that the desire to "do good" by force is a good motive. Neither power-lust nor stupidity are good motives.
A rational man never distorts or corrupts his own standards and judgment in order to appeal to the irrationality, stupidity, or dishonesty of others.