This is still technically a cancellation due to an airline schedule change. You’re not likely to get a document from the airline that uses the magic words your flight was delayed by a mechanical issue.

It’s sort of like the Southwest meltdown in Dec 2022 - the first couple days were coded as weather, but most of that event was “operational change” cancellations because they couldn’t get aircraft to where they needed to be to make flights happen as scheduled.

The wording of the hazard on the Amex and Chase coverage is intentionally specific to limit the cost of these policies. There’s a massive gap between what most people expect from these policies based on the headline marketing text of “6 Hour Trip Delay” and what coverage the policies actually provide based on their actual policy language.