blackfeld: Why should Apple prevent the release of a port of a 15 year old game on another storefront?
shmerl: Because they are Apple. Messing up others is their routine. See
what Icculus has to say about them.
blackfeld: I guess the main reason for missing GOG versions is simply due to piracy concerns by both Aspyr and Disney.
shmerl: That makes no sense, Disney already released both KoTOR games here (just not the Asypyr's versions). And Aspyr said in the past they are interested in GOG release. That's why I suspect Apple is the cause of this mess.
There is a big difference between Disney being the (main) publisher of Windows/console versions and license/trademark holder and Aspyr, which is only the publisher of the Mac/Linux/iOS/Android versions.
Aspyr has to pay for the rights to port and publish Disney's IPs to macOS/Linux and mobile and they only get paid when someone buys one of these platform-specific ports.
The concept of SteamPlay or similar "buy once, play on all devices" is not really working for Aspyr and Feral because they don't get a cut of the Windows purchases.
KotOR 1's Mac version is on Steam, Aspyr released its port both on Android and iOS. Apple doesn't get a 30 % cut off of the Steam release, the same applies to Google Play. KotOR II: The Sith Lords Remastered has been released on Steam for all platforms (Windows/Mac/Linux) -- with Aspyr being the publisher and porter.
Apple does not prevent Aspyr or Feral to release their ports on competing storefronts. There's no evidence or proof of that. Ask EddeDuck or AspyrBlair, they will tell you the same.
I'm pretty sure the only reason for them not releasing ports on GOG (self-published titles like Layers of Fear or Observer being the exception) is money. GOG is a relatively small and European-centric storefront, and it's DRM-free. There's no way to "protect" a relatively expensive Mac/Linux port of an older game.
People still pay good money for Aspyr's ports of the Monkey Island: Special Edition, KotOR or Jade Empire on the Mac App Store. Selling the same titles for a few bucks during a Steam or GOG sale is not a very attractive option for a porting company.