Yes, it is ethical. In many countries it is legal for humans to walk around the public square and overhear all conversations.
It is NOT legal to install cameras that record everyone's conversations, much less sell the laundered results.
Pre-2023 people went on Twitter with the expectation that their output would be read by humans.
A traditional search engine is different: It redirects to the original. A bastardized search engine that shows snippets is more questionable, but still miles away from the AI steal.
Many countries have freedom of panorama, which means it is legal to video record the public square. I'm not aware if anywhere has specific laws on mounting the camera on a robot.
If the background of the issue is as Musk described, then it certainly is not allowed by twitter’s robots.txt, which allows a maximum of one request per second.
I do a lot of data scraping, so I’m sympathetic to the people who want to do it, but violating the robots.txt (or other published policies) is absolutely unethical, regardless of the license of the content the service is hosting. Another way of describing an unauthorised usecase taking a service offline is a denial of service attack, which (again, if Musk’s description of the problem is accurate) seems to be the issue Twitter was facing, with a choice between restricting services or scaling forever to meet the scrapers requirements.
Personally I would have probably tried to start with a captcha, but all this dogpiling just looks like low effort Musk hate. The prevailing sentiment on HN has become so passionately anti-Musk that it’s hard to view any criticism of him or Twitter here with any credibility.
Musk is trying to have his cake and eat it...
(Clearly it's not a public square, but his position is incoherent).