I am presuming that by the Clarion being "nice enough" that it was covered. Thus, duty of care met.
As to delay/cancellation under EC 261/2004, that will depend on which flight it was that was delayed and why. The planned runway closure for an inbound won't likely do it, but if there was an unrelated incident closing access to the airport, that would likely be "extraordinary" and could not have been remedied.
There is no right to be rebooked because you might misconnect. As you can see, carriers would prefer to take the risk of a misconnect, even if it entails paying delay compensation, than proactively reroute.