The question is large and complicated, and people can agree to disagree. There's nothing wrong with tweeting vulns: The company is at fault, we can defend ourselves now that we know about the vuln, and it's a big PR disaster for Apple.
A past conversation: https://news.ycombinator.com/item?id=14009937
No, no it's not strictly more ethical. It's not even strictly safer, which should be an even easier question to answer. The baked-in assumption in your logic is that users have no options other than waiting to patch. But, obviously, they do, and keeping vulnerabilities secret deprives them of those options.
