Z’uush

A member spices of the Federation. The Miners of this spices started a rebellion at the beginning of the story and acquired Terran weaponry for this conflict.

Biology
In 1.Chapter: Army Surplus T’sunk’al was hiccuping. It is later confirmed as a biological quirk of the species in stressful situations.

In Chapter 3: Precious Cargo it is established that Z'uush have:

-Secondary Manipulators

-Tend to loose control over their bowls in extremely stressful situations

-have an exoskeleton

-have breathing a breathing orifice

-have twelve eyes

Federation:
In Chapter 3: Precious Cargo it is established, that the punishment for gunrunning, smuggling,... for a miner is an extended (Most likely indefinite) stay in a forced labor camp.

Drugs
Slavers Dust is mentioned in Chapter 3: Precious Cargo.

Treatment of the working class (Miners)
Knowing the Federation, it is pretty likely that, their government choose these draconian measures to stay comparative in this exploitative environment.

Or, alternative, this mirrors the treat meant of minorities/slaves/bondsman in our history....

Biology
Predation

The tendency to void ones bowls in stressful situations could be part of their fight/flight/hide Reflex. If they where preyed apron, for a long part of their developmental history, this may be a reflex to make one as unappealing of the predator as possible.

Their twelve eyes (depending on their position) may also indicate this. Prey (deer, cows, horses) have their eyes more to the side of the head, while in predictors(Human, wolfs) the eyes tend to be focused forward. And than there are spiders.