I agree: "object-safe" is not a good description, and dyn Trait-compatible or just dyn-compatible is a much better term that would help people understand it more easily. This has come up a few times.
Potential concrete next steps: make a small lang proposal to use "dyn-compatible" rather than "object-safe" everywhere, and assuming we get consensus to do so, send PRs to change user-visible instances of "object-safe" (e.g. in error messages, documentation, and the reference).