I was assuming it meant 'Significant New Information'-lessness. Which perfectly captures why I've found the discussion frustrating, since there was loads of speculation on no concrete information. So even if it was a typo, I think it's a great new word

It's not a typo.

Update - I'm wrong. In the comment dang says

  each twist with Significant New Information (SNI)—but to downweight the ones that are sneeless

So it definitely isn't a typo for senselessness. I should have known dang types what they mean!