Auto-deploy rules to deploy updates is a cool feature because it automates rutine tasks and it was introduced in SCCM 2012.
I wanted to use auto-deploy rules to deploy updates to servers as available. Unfortunetely, this is not possible.
But fortunately there is a workaround - set deadline long time in future (it is possible to set max 12 months).
If auto-deploy rule is set to evaluate each month and set to append existing update group, it will always extend installation deadline and thus never install updates. But it will be possible to go to server and install updates manually!