Yeah. I would say if we are going to keep NA for North America (which according to ccTLD is Namibia), then there is no reason we can't use [AS] for Asia.
Personally, I think the use of NA and AS will be less confusing for users, but I'm not opposed to using user-defined codes.
For instance, I'm fine with not adhering to the ISO 3166-1 alpha-2 and using NA (North America), EU (Europe), AS (Asia), SA (South America), AF (Africa), etc and use short hands for continents. Then under each continent region, use the TLD codes for releases in countries like we do in the [EU] categories. NA where [US] releases don't require TLD, EU where [UK] releases don't require TLD, and I guess AS where [CN] wouldn't require TLD. I don't know what the prevalent TLD would be for AS, it's also hard to tell which countries some of the games are from.
I'm also fine with us doing something like [XA] for Asia, [XE] for Europe, [XN] for North America, and [XS] for South America. But then you have the issue of what is Africa [XF]? Maybe scrap logic and just go ordered by use [XA] for NA, [XB] for EU, [XC] for AS, [XD] for SA, [XE] for AF, and so on?
I don't necessarily see a need to use ccTLD for categories, but using ccTLD for individual entries does make sense. If our categories serve to represent continents rather than countries, it wouldn't be necessary for it to follow the ISO, because it's not relevant.
Edit: Hmmmm, but that makes JP as a region a wrench in the works, because it would be categorized under [AS] wouldn't it.