OP here- it seems my post was poorly drafted. Not inquiring about mileage compensation.

The issue is that airport staff are saying the delay is weather related BUT the EP desk is saying it's crew related. AA hasn't given or offered any vouchers yet. They're saying- wait till you to get JFK.

So to rephrase my question- what does one typically do if the cause of the delay is unclear, or as per one of the posts above, ambiguous? My cousin doesn't live in the US and I've never been in this situation before. Should he push for vouchers?