Not only did I say that but I also gave the specific Ubuntu version as well!

That's too bad :( As a Linux user, I love it when game studios support Linux and make a point to buy their games more often.

Steam for example has a "SteamOS + Linux" filter so exposing your game as Linux compatible means exposing it to all Linux users.

Almost everything that works on steam works everywhere. Letting the dev specify a supported distro would be a huge misfeature not unlike websites that used check user agens and refuse to work outside of Internet explorer.

People would start pretending to be Ubuntu to install games.

Yes it seems better to whitelist specific explicit Linux-configurations (version, window-manager, sound-setup, etc). Like we officially support this, if you are using something else use the forums to discuss with other users but we will not investigate your issue.