Correct. In fact, when HF17 introduced eternal content edit, it became possible to use this technique to edit posts. The hardfork allowed it, but no witness ran code to allow it.
By HF19, some witnesses did allow it, but it was still random if it would persist to irreversibility.
I tested it before the UI allowed it and sometimes I could get an edit irreversible. So that's one reason I think this would work now.