When you buy a game do you complain that you don' get the pre-order bonus ?
The code is like a pre-order bonus, reserved to a few people that follows me on patreon.
In addition nowhere on the itch page the code is mentioned, it's just not sold here.
Please remember that without the patreon crowd there would be no game to play, they trusted me before anyone and deserve some perks for that.
Finaly the code will be made public soonish.