Eh, thing is, he doesn’t need to persuade anyone who is against the mistreatment of others that the idea is horrific - they already know this without having to have anyone point it out, and are already firmly against proposals like this.

But he does need to persuade the chunk of the population that are indifferent to the plight of migrants, or who believe that cruelty is an effective tool, or who embrace cruelty for itself, to also reject this proposal. He won’t want to draw their attention to the awfulness of the idea, as this group will be disinterested at best.

Without them on board, it will be considerably harder to force the Tories to back down, and though Labour will win the next election and can end any measure then, that still leaves time for tens of thousands of people to be forcibly removed to Rwanda.