It does seem strange that files from an OS9 disk (essentially a "permissions-agnostic zone") copied to an OSX disk (where again?) provided such resistance to being trashed/erased. They should not have.
I can
partially confirm that. A long time ago, I tried to remove the old OS 9 from an OSX HD and many items gave a similar message. I ended up putting system folder files in the Trash as files, not the whole folder. As I recall (vaguely, it's been awhile), pressing option key while emptying Trash would work and I did not need to recur to Onyx. However, these were system files, not pictures or graphics. I don't recall any problems with those...
