Orbital Strikes are called in by an FAO (Page 29)
As well as the Khazari and Colonial Union Defence Force lists, FAOs are also missing from HOF droids, HOF Alien and the FWC Bug Colony
The Andrayadan, Kraytonian, Ogrethulhu and Grey Alien lists don't have FAOs but the commanders can call in artillery / orbital strikes
Therefore
a) add an FAO to the list
b) allow command units to call in orbital strikes
c) you can buy as many orbital strikes as you like but you can't use them
I'd say b as it saves messing around with points.
And have you considered pimping up your orbital strikes with a couple of tech upgrades?