Lar was referring to a hypothetical multiplayer game mode, rather than a collaborative mod tool (both mod tools and multiplayer support were being discussed when he gave the comment I quoted above). Presumably if there is some kind of add-on for the game that includes multiplayer support, then Larian figures mod tools would be more worth the effort than for 'just' a single player game (or at least did at the time the comment was made).
D2:ED initially supported multiplayer, but it was dropped when it became too restrictive on the plot and quest design.
The default forum search date range is one week, though even changing that I've noticed it not turning up results a couple times searching for things I know I posted (possibly a word length limit, where short words don't get added to the index?).
