Let me restate the issue: M-x mark-word RET will highlight the word at point. M-: (mark-word) RET will *not* highlight the word at point.
My understanding was that interactive call of mark-word highlight the region, while non-interactive call do not highlight it. Is this wrong? `org-mark-element' and `org-babel-mark-block' are not different to `mark-word' here. -- Bastien