IMO this is already covered by rule 2.3.
If it is obvious to me that someone is tanking at any point in the season, they are subject to aggressive unilateral punishment with no rights of appeal.
The general requirement is to field a full pitching and hitting lineup. Stuffing the bench with NA and DL players has always been acquiesced to. The odd NA or DL player slipping into the starting lineup is sometimes also seen as okay, typically in the short-term, and depending on the specific circumstances (sometimes MLB players fail and get demoted unexpectedly; sometimes a rebuilding owner happens to get hit with like eight DL players at once).