Ultimately if you cannot abide by the rules for whatever reason - even simple human error or forgetfullness - you shouldn't really be using the forum without expecting moderator intervention. On most of the forum a little discretion is used, however when it comes to the MM where money is changing hands a misleading post can have much more serious consequences. It's the same when it comes to competition between threads getting out of hand due to uncontrolled bumping.
Think of it like driving a car. If you forget to indicate I'm sure it would be understood by a police officer that there was no malicious intent, but this doesn't necessarily change anything. The law would still apply to you to protect the safety of yourself and others due to the environment you are in.
Too long, didn't read: Stick to the rules or expect mega slaps in the MM