My understanding is that this Code as a whole is not intended only for ACM members, but all computing professionals. I made a comment for clarification in the Misc sections on this, but there hasn't been a response there.
So, yes. I do think that ACM members should be champions for this Code. But I don't think that the word "ACM" should appear anywhere in this Code (outside of perhaps the title and/or some explanatory text in the preamble), so this idea should be expressed somewhere else. Based on my understanding, I think that every Principle in the code should be written in a way that applies to all computing professionals, whether they are ACM members or not. I would be OK with a broader statement that does encourage all computing professionals to encourage and/or support adherence.
If my understanding is wrong and the intention of this Code is only for ACM members, then I would change my opinion here. Instead, I'd object to the use of "computing professionals" in other parts of the code and request that it be changed to "ACM members" to better reflect who this applies to.