Couldn't get Big Spear Diplomacy achievement

This achievement requires player not to use Spear of Adun in mission “Salvation”.
So I did not click any of bar abilities (active abilities) and finished the mission without getting any achievement. I would like to know if there are others having same problem.
Or do I also have to avoid using passive abilities too? That will be funny, then I can not have auto-gas collector/walk in pylon field to get buff/warp with Stargates/let overcharged Nexus to hit any enemy etc.

Might want to run a search before posting. At least a few posts on this already. :slight_smile: