They did. [0]

> This port was initially done by Edward Rudd for providing Gemini Rue in a Humble Bundle when the AGS backend was Allegro 4. Currently, it uses SDL2.

[0] https://github.com/adventuregamestudio/ags/tree/master/OSX

Unfortunately, Edward's project is just a runtime for running AGS games on Mac. The AGS Editor (the topic of the original post) is still Windows-only, and will likely always be due to its deep reliance upon Windows GUI libraries.

Oh nice!

Is it too hard to port?