(Apologies for the double post; should've remembered this earlier)
This idea came from a discussion on whether or not the new "Alternative Europe" map should have superbonuses. There was a (rather long) discussion about it in [this game](
http://WarLight.net/MultiPlayer.aspx?GameID=2720351) which was (deliberately) never started.
Also, the reason why it is important (if you consider the AI's behaviour important at least) to not zero-out but actually remove bonuses is because the AI *will* try to complete superbonus, *even* if its value is zero. Discussion about that (and link to example game) in [this thread](
http://warlight.net/Forum/Thread.aspx?ThreadID=3739).