I'd not seen that part of it before. I think the trick word here is "manifestly", and some sources seem to indicate that this means that the people would have to have expressly given consent for onward processing.

For example: https://iapp.org/news/a/publicly-available-data-under-gdpr-m...

Also Article 9 seems to be restricted to non-processable data about sensitive matters.

Anyhow, it's definitely a good example of how convoluted the language around GDPR can get, and how much of a minefield it is to try to follow it.

The usual caveat applies, I'm not a lawyer.