Donglegate isn't about conference staff having a quiet word with people in private. It's about one person getting fired for offending another, and that person eventually getting fired because of community lacklash.
If all that had happened was that somebody got offended, privately told a staff member, and then the person causing offence had been privately spoken to - which is what the PyCon code of conduct required - we would never have heard about it.
Now, the possibility that the offendee might shame me publicly and cause me to get fired might have a chilling effect. But that's nothing to do with codes of conduct. If anything, publicly shaming somebody that offends you would be in violation of the code.
Your assertion was "You will need to remain silent if you bully, harrass, intimidate, stalk, stereotype, or belittle." The guys in donglegate did none of those things, and yet they were in fact reported to staff. Over private words.
My point is that you never know what is going to offend someone. This CoC says that you agree to be removed from the premises if someone gets offended, provided they are of proper minority status, which in itself invalidates the whole idea that this is a non-political CoC.
The code actually says that you agree to be removed if you "wantonly behave in a manner inconsistent with" it, and only one of the paragraphs mentioned minorities: they chose to lead with a general requirement to treat others with respect, dignity and empathy, regardless of who they are.
This is not a code of conduct designed to punish accidental "thought crime" against minorities: it is designed to prevent intentionally or recklessly offensive behaviour towards any and all conference attendees.
I do not doubt the good intentions of the authors. They clearly spent a lot of time thinking it through, and came up with something they felt was the most inclusive, and opened it up for comment. None of that was required of them, yet they did it, and that is admirable.
Sure, it was just one paragraph (or 1 of 5 bullet points in the pledge). Let's look at another:
"That if I become aware of any behavior by others which is inconsistent with this pledge, I shall take immediate action to report such behavior to event organizers;"
Coupled with this in particular from the previous quote: "examples of minority groups include..."
40% of this pledge says: If an event-goer commits and/or witnesses a behavior that could be offensive to a minority group of some sort, thanks for your money but we'll be taking those badges back, unless this hourly event staff member thinks you're cool.
This is exactly the point I'm making. Their problem was that they spoke aloud in a manner that does not properly reflect the sensibilities of someone they weren't even addressing.
EDIT: Herein lies the rub, and some might say the whole purpose behind CoC's. As a cop might say, you might beat the charge, but you won't beat the ride. Even if you've been tried by event staff for wrongspeak and found innocent, your whole experience is ruined.
If one did that one would, of course, be wrong, both in the general case (the jokes were silly grade-school level puns that would concern no well-balanced person) and the specific case (if anyone was being stereotyped or belittled, it would be males, given that they were telling the jokes about a male presenter.)
You, like many others, miss the most important part of DongleGate. She shamed the supposed dongle-joke offender on Twitter with their picture, which was unambiguously against the Code of Conduct, for it bans harassing photography. She did not only fail to see the hypocrisy, her actions were deemed heroic and she compared herself to Joan of Arc.
This was a clear sign to anyone paying attention that Codes of Conduct were never about policing behavior objectively, but instead were to be wielded as a weapon to shame and attack particular groups of people based on a political ideology of victimhood.
You don't see that as having a chilling effect?