I would see it more like a conversation in a public place / at a convention. Sure, anyone can join the conversation and listen in. I would still be unpleasantly surprised if someone posted a recording on a website.

Most IRC clients are logging the conversation by default, and everyone knows it. Even if they werent; you're speaking in public.

But there's a difference between recording and publishing. We know that everyone is recording, but publishing the logs isn't as common and can be surprising.

It's speaking in public. Common or surprising isn't legally relevent. And since it's the internet; it can't be. It's one reason why sovergn groups of humans are so fantastic.

Not legally relevant doesn't mean not relevant.

And freenode does have a clear policy on public logging, requiring you to disclose that you are logging beforehand or get permission before publishing. [0]

[0] https://freenode.net/policies#public-logging

Lots of things that are legal (or legally irrelevant) are not socially acceptable.