For the record, I do not use Safari 3.0.4
Some of my users do. They report the issues to me, I replicate and validate them, then post them here.
I do not think my job is evangelizing my users and helping them into upgrading their browsers. Mostly, because it would be an impossible and/or fulltime thing. My job is to make sure the forum works for them.
Some solutions for me are disabling the advanced editor, or detecting useragent and displaying a prominent message that says "your browser is not supported" or something else. Giving the appearance that something works then doesn't is not a good user experience, either make it work, or display a message saying that it doesn't and why.
I'm trying Safari 3.0.4 on Windows, and the editor seems to work. Though I seem to have issues with other JS that I'm still trying to track down. I can use quick reply without an issue, though submitting it doesn't show the post unless I do a refresh. Is that the behavior your actually saw?