Why unrated? If I beat a darn good machine, I want my rating to reflect that... And if I loose, well I probably won't mind it going down either since I lost in the first place... As a matter of fact rated games are probably more chalenging, since there is a motive to try and win against the machine - there will be a reward in the end.
The only thing I ask is to know if I'm playing againsta an engine or not. Even though it may bias a little my way of play, it will go a long way against the possibility of me feeling defrauded when I find out about it later on in the game (if I find out, that is).

About the user agreement... Well, in my oppinion it should be changed though maybe not right now (the subject is too hot for most people to think about the big picture and abstract from this particular case). But in correspondance chess (and other games) usually the help of books, move databases or even computers is not forbidden. Some of those (if not all) are even good ways to learn how to play the game. And since it can't be controlled anyway...
Maybe BK's user agreement could say something in the lines of "everything is allowed however it is common courtesy to warn your opponents of any outside help you may be using" (I won't suggest a proper sentence... my english just isn't good enough to detect all possible side interpretations, I'll leave that to others).
Oh, and would everyone stop calling it "the rules"? The word guidelines is written all over that page. It means (even according to my bad english) that there can be exceptions to what is written there.

Since this post is getting huge (at least as seen in this tiny message box) I've highlighted some of the key words in it. Just to sum it up.

[Hrqls - I had the opposite problem. People used to call me pauloaquia in another site, preciselly because of the underline ]