Like you, I elected to purchase Disney
travel insurance and am booked to fly on Delta April 28th. To quote my policy, it states under the heading TRIP CANCELLATION AND INTERRUPTION "This coverage does not cover loss caused by: (i) carrier-caused delays including an announced , organized, sanctioned labor union Strike that affects public transportation, unless the Insured's coverage effective date is prior to when a strike is forseeable. A Strike is forseeable on the date the labor union members vote to approve a Strike."
I just spoke with a travel insurance specialist who indicated that, since I paid booked and paid for my trip/airfare prior to the strike vote yesterday, any ramifications of a Delta strike would be covered. He assured me a travel specialist would find a comparable flight for April 28th should Delta be inoperable. I fervently want to believe the specialist with whom I spoke as this will be our first trip to Disney . . .