Resumindo: Holonet (a única ferramenta de comunicação adequada de longo alcance) estava sob controle imperial. Os rebeldes NÃO possuíam equipamentos de comunicação de longo alcance.
Se você olhar para a UE, a informação foi recuperada pela ex-namorada de Han Solo, Bria Tharen, em um posto imperial durante o que foi, na verdade, um ataque suicida. Eles usaram o comunicado do posto avançado para transmitir as informações para o navio rebelde no sistema, não tinham outros meios de comunicação. O navio em si era um corredor de bloqueio, sem equipamento de comunicações de longo alcance e - para repetir o primeiro parágrafo - nenhuma chance de transmitir com sucesso via Holonet.
Yes, Count Dooku succeeded in using the HoloNet for Separatist propaganda purposes, but Republic forces were quick to shut down those Shadowfeeds.”
He looked at Ison. “If memory serves, COMPOR itself was established as a result of the navy’s actions at the time.”
ATUALIZAÇÃO:
A história de como Holonet surgiu sob o controle do Império é coberta pelo livro "Tarkin", da New Disney Canon. Em suma, os separatistas sob a orientação de Dooku seqüestraram o equipamento de Holonet e espalharam a propaganda de Holonet. Como resultado, Palpatine passou a controlar totalmente o governo 100% dos equipamentos e transmissões da Holonet.
It had been just nine months after the Battle of Geonosis that Count Dooku’s scientists had succeeded in slicing into the Republic HoloNet by seeding the spaceways with hyperwave transceiver nodes of a novel design. The Separatists could have kept quiet about the infiltration and tasked the nodes to gather intelligence about Republic military operations. Instead, Dooku—as if suddenly intent on winning hearts and minds rather than defeating the Republic with his droid armies—began using the HoloNet to broadcast propaganda Shadowfeeds, providing Separatist accounts of battle wins and disinformation about Republic war crimes, and in the end spreading apprehension among the populations of the Core Worlds that a Separatist victory was imminent.
It was, however, Separatist success in jamming Republic communication relays that had brought Tarkin into play. Together with operatives of the Republic’s fledgling cryptanalysis department and elements of the Twelfth Army, Tarkin had been sent to Murkhana both to spearhead the invasion and to oversee the dismantling of the Shadowfeed operation.
With the Emperor’s proclamation of the New Order, some aspects of the HoloNet had come under strict Imperial control, as much to provide the military with exclusive communications networks as to censor unauthorized news feeds.