I think the most logical reading of what has been posted is that at some point in the past bedelman had a RTW ticket booked through CX that s/he sought to get partially refunded due to one or more sector being cancelled, CX refused it and claimed DOT rules did not apply when they were pointed out to them. The implication (not confirmed) from bedelman's post is that s/he then raised a complaint with the DOT which was upheld, and CX were compelled to pay the pro-rata refund, the suggestion being that this (a formal DOT complaint) was an avenue george.steel might take in seeking satisfaction of a similar partial refund from AA.

CX would never explcitly publish anything saying that (e.g. because they're Hong Kong based) they had no responsibility to refund under US DOT regulations in the appropriate circumstances because it's not true and they know it. They (in common with many carriers) will just fob passengers off with such untruths (see also EC261) in the hope that people are insufficiently versed in the intricacies of international aviation agreements to challenge what they're told.

Whether this behaviour is down to ill-informed customer service agents or a corporate 'first line of defence' in minimising cash outflows due to refunds, who knows? I'm more inclined to believe the latter.