"The Galactic Government deploys individuals from all of the races, so why are the helmets designed for humankin!?" ~Unidentified Yurkian Serviceman.
The Galactic Government is a fledgling republic created primarily for the purpose of granting diplomatic access to each and every planet and sentient species encountered in the Milky Way Galaxy. Being a neutral power, they rely on a voting process undertaken by all of their representatives to determine whether or not they actually intervene in armed conflicts. When the vote is cast and intervention is greenlit, they deploy peacekeeping forces to secure civilian infrastructure and suppress aggressors.
GC has largely sent it's peacekeepers to deal with pirates throughout the Milky Way, as they represent a threat to peace and security throughout. Otherwise few hostile sentient elements have been encountered thus far.