Plug in Yes, but in What?
He doesn't actually say Safari, he may have been talking about CSS Sculptor or Dreamweaver.
I attach a list of my Safari plugins. There are many, but they all seem to be collected under a few reputable and unrelated categories and certainly nothing obvious like "Community Toolbar". Or do you see something suspicious?
I'm not sure I mentioned, but there is a Sheepshaver icon in the error dialog.
I vaguely recall that Vuze may have had a Community Toolbar thing it wanted to install. But when I use the 'uninstall plugins' command in Vuze, there were only 4, apparently unrelated plugins.