It is irrelevant that the strike involved their employees.
Had they simply cancelled your flight they would owe you nothing*, as it was an extraordinary circumstance.
Kudos to them trying to get their customers to their destinations.
*They would be obliged to reroute you on their next available flight, or refund you any residual value of the ticket.
Last edited by ExXB; 25th Mar 2018 at 15:03.
Reason: Typo