For a schedule change, I believe this is the rule you're referring to. But I don't think anything will override the change in Country aspect.
American Airlines has a Schedule Change – AA Flights:
300 - Mile Radius
The 300-mile radius option may be applied if the Schedule Change results in one of the following:
Discontinued service without an alternate protection agreement
An extended connection time equal to/greater than 4 hours
Invalid Connection
Note: If there is a valid connection within the same origin/destination with an arrival time within 2 hours of original ticketed schedule, 300- Mile Radius does not apply
An involuntary connection requiring the customer to overnight on either the outbound or return segment\
The 300-mile radius option change must be made at the time of original ticket reissue.
Discontinuation of Service:
If American Airlines has an alternate protection agreement the 300-mile radius option is not allowed.
Itinerary must contain AA Prime, AA*/US, or US Prime Space Only
If there are no acceptable options to the customer's original ticketed destination/origin, may book AA Prime, AA*/US, or US Prime space only to an alternate AA airport, within a 300-mile radius of the originally ticketed city within the same country
The new flight must be rescheduled for the same ticketed date of travel but may be earlier or later than the originally scheduled flight time.
Use lowest available inventory in the same cabin as ticketed
If unable to book in the same cabin as originally ticketed, an alternate flight must be selected.
If the customer has chosen an alternate AA or US airport, they may use that airport for their continuing or return journey.
This change must be made at the time of original ticket reissue.