I remember studying this book in school myself and thinking that this woman was very arrogant. You might want to analyse the series of sermons that she gives the children regarding evolution and how she views the Waknukians compared to the new form of human that her kidn represents. She gives a series of sermon-like speeches to the children that clearly identifies her own world-view and the position of dominance that she feels her people to occupy. Consider the following example:
Whether harsh intolerance and bitter rectitude are the armour worn over fear and disappointment, or whether they are the festival-dress of the sadist, they cover an enemy of the life-force. The difference in kind can be bridged only by self-sacrifice: his self-sacrifice, for yours would bridge nothing. So, there is the severance. We have a new world to conquer: they have only a lost cause to lose.
It is perhaps ironic that for all the talk the Sealand woman gives about the necessity of the Waknukians and "old" humanity dying so that the "new" humanity can thrive and live, she ignores the implications of her own teaching. If humanity is a species that evolves like every other creature, then the telepathic stage of humanity that she represents is just another one of those stages. She is displaying the kind of arrogance that finds its parallel with David's father in identifying a perfect form and treating any deviation from that form as a mutation to be stamped out and obliterated.