ok SAT I guess you are saying that he has the right to International rule 80B because the contract itself has not been changed, updated and put online saying that DL will NOT endorse the ticket to another airline. DL has the right to alter the contract verbally in form of Customer Care without having to rewrite the contract itself...

Authority of Delta Employees & Ticketing Agents
Except where otherwise provided by law, no Delta employee or ticketing agent has the
authority to alter, modify or waive any provision of the Contract of Carriage unless
authorized by a Delta corporate officer. Delta appointed agents and representatives are
only authorized to sell tickets for air transportation pursuant to the approved fares, rules and
regulations of Delta. This rule supersedes any conflicting provision in the contract of
carriage.

I would say that this backs me up...

SAT like I said in an earlier post... I originally went with the believe that a schedule change is qualifying for other airline reprotection due to international rule 80B but our corprate office corrected me on another situation that i faced earlier this year.