Well I have no trouble editing Hourglass Hex Chess, which is a bigger file than Nearlydouble. Unfortunately that appears to demolish both our theories, as Hourglass Hex has comments as well!
When my attempt to edit fails I get error 403. When it is successful a garbled version of the variant appears on the next page - but with the "view submission" link at the bottom so that I can continue to the page as edited.
When my attempt to edit fails I get error 403. When it is successful a garbled version of the variant appears on the next page - but with the "view submission" link at the bottom so that I can continue to the page as edited.