What you are saying makes no sense at all. It is not optional to keybind the controller. It is locked in. If it wasn't supported I would have to do that through a 3rd party method. It is clearly in the game...
Maybe controller support is something you shouold look at and maybe controller only servers on PC?
How can you say the controller is not officially supported? The controller is included as part of the controls of the game. The controls are fixed. they cannot be changed. This is not an external source to control in the game. It has been inputed and locked by Bohemia in their game...
When you buy DayZ, you do not have to map the controller. You do not have to use Steam to map the controller either. There is a controller choice in the menus.
How can you say it is not a supported method by the game?