I don't think we can do that. The GameOption in the XML turns the building on/off depending on the status of the option. This is so even with the update transactions, ie if you have it in the update transaction it will turn the building or unit off not the update. We would need to duplicate the hunter line of units one requiring the building and the aggressive on and one not requiring the building and the aggressive off.
It may be possible with a dummy building that requires aggressive on and a update transaction that has an and dependency of that building but then you would have to get out and back in after setting the option for it to have any affect because the XML is loaded before the options can be set.