A safe guess may be that theymos does not want to create any type of ToS agreement with users for the same (or similar) reasons why there is not an "official" set of rules... it has to be the unofficial (official) set of rules.
No "official" set of rules was ever published, because if rules are set in stone, then people will come up with clever ways to bypass them, and then complain when a moderator takes action. This is however a very good thread to read to find out in general what you can and can't do. I do believe it should be stickied, but kept as "unofficial"