What kara said; the Shivan Manifesto is basically speculation, so it's no more valid as canon than, say, Inferno or the Capellan BBQ theory. IIRC it has a number of holes in the logic, too, and relies a lot on supposition.
I'd recommend against putting any fanon type stuff of this ilk in the wiki, as it's liable to being misinterpreted as canon, and it also risks people not developing their own ideas. At most, we should put external links to discussion thread about this and other theories, but I think highlighting one theory alone - be it the SM or otherwise - is somewhat unfair to everyone with their own theories. IMO, the only reason the SM is seemingly so popular in this regard (vis-a-vis other theories) is because a) it is quite long and b) most campaigns can't, don't or won't publish their own ideas for obvious reasons.