The Galactic Trade Fleet had been politically falling behind for a considerable amount of time. With the invention of Dimensional Drives the Galactic Trade Fleet was no longer the backbone of the galactic infrastructure. Their ways were seen as archaic and they were viewed as anti-progress.
The Galactic Trade Fleet was in opposition to Intergalactic Expansion. They viewed Zvelvist, Solar Seed as in important cultural monument. Refitting it to be used as a warship during Intergalactic Expansion was seen by many as the start of the genocide. The Galactic Trade Fleet's opposition was ignored and legally stamped out.
They were eventually vilified as anti-galactic. Governments refused to trade with them at first but violence soon followed. With popular sights set on Intergalactic Expansion most people did nothing to defend the Galactic Trade Fleet.
The Extinguishing of Emberhull was a major turning point. It effectively put an end to organized resistance and fractured the Galactic Trade Fleet into several groups. The genocide continued for many generations afterwards in the form of history erasure and forced assimilation.
Much of the teachings of the Galactic Trade Fleet were incorporated into the culture of ships sent to engage in Intergalactic Expansion. They were well versed in staying alive in space indefinitely. Incorporating the teachings both helped logistically as well as muddying the meaning and origins of Galactic Trade Fleet traditions.