I'm unaware of a "maybe notice" provision for the safe harbor match. My understanding is unless an amendment removes the safe harbor match for a year before the year starts, it's required by plan document. You can stop a safe harbor match but you have to give give 30 days notice to participants and you are subject to testing.
I'm also unfamiliar with the concept of the safe harbor notice itself being an amendment to the plan but I'm not saying that it is not possible.