How entire goal was to eradicate the most promising young people of the Labour Party, ie the country's likely future leaders. Iirc his idea was when the most promising political talents are dead, the party has to settle for less and will lose votes.

So it wasn't really mental gymnastics, it was a conscious attempt to curb a particular party's future. It's evil and it's nuts, but it makes logical sense. It's not dissimilar from genocide motives in that sense, just on a smaller scale.