The fare from that post is B2 - an unrestricted, fully refundable B-fare.

When I asked about upgrading two recent flights to GRU, I was told that I would have to purhcase B2, which was far more expensive than BLXBR6M and BLWBR6M (which also have equivalent fare bases for EZE and GIG according to Expert Flyer), in order to upgrade using only 10,000 miles. In both cases, the agents talked to the tarriff department to confirm. I was quoted this rule, which is on AA.com:

Unless otherwise noted, a full-fare ticket is one that is booked in Y or B and is unrestricted, requires no fee for change or cancellation, has no advance purchase requirements, and is fully refundable.

The problem with the cheaper B-class deep S America tickets is that they are not fully refundable (10% fee).

Granted, it would not be unfathomable for 4 AA employees to give wrong information, but that's the story I was given. I didn't persist because the lower V-class plus miles and copay was a better deal for me personally.