AA service to SE Asia is all code-share. DL service is mostly via NRT on DL/NW metal. You likely have a decent investment in the DL program right now in terms of accrued miles and the like, too.
Unless you plan on shifting wholesale to AA going forward, spending the $1200 is a waste of money, IMO. Besides, you can probably get Plat with them for way less money if you do it via their traditional challenge rather than using the DEQM approach.