Here is not just scraping though, it is also using that data to create other content and to potentially also re-publish that data (we have no way of knowing whether chatGPT will spit out any of that nor where did it take what is spitting out).
The expectation that social media data will be read by anybody is fair, but the fact is that the data has been written to be read, not to be resold and published elsewhere too.
It is similar for blog articles. My blog is public and anybody can read it, but that data is not there to be repackaged and sold. The fact that something is public does not mean I can do whatever I want with it.
ChatGPT doesn't get inspired, the process is different and it could very well spit verbatim the content. You can do all the rest (depending on the license) without issues, but once again this is not what chatGPT does, as it doesn't provide attribution.
It's exactly the same with software, in fact.