Independent of the weapon airburst should be able to be added to every smartlink.
There is a special "smartgun" slot, however Airburst ist not shown in the list of available options.
This is likely caused by the Airburst requiring “launchers” which it does not find, because it is build into a smartgun system. Also it would not make sense to restrict Airburst only to launchers, as e.g. an Ares Alpha or Yahama Raiden comes with an underbarrel grenade launcher and thus could benefit from Airburst, although those weapons are assault rifles and not launchers.