To me, this reads like a fairly transparent play to expand the Overton window[1]. There is an almost total lack of evidence for the merits of his argument, just bald assertion and a lot of buzzword-rich waffle.

Half the earth is both outrageously huge and within the realms of possibility. If we debate the merits of it, then we're more likely to entertain more modest proposals.

[1]https://en.wikipedia.org/wiki/Overton_window