Even though a Star force realm expert could survive in space, that is just surviving. They couldn't hope to travel between stars. They'd die halfway through. And because of the generations of Star force realm cultivators who wish to travel through space the technology for space exploration advanced steadily. They've already reached their satellite planet and have even started colonizing it. They've even sent their spacecraft to their next nearest planet. The sixth one from the solar star. If they were given a few more hundred or thousand years they would've reached Triton and the outcome is known to everyone. Without any rules, they'd have plundered the planet and colonized it after killing all the powerful cultivators. After that, the others would either be slaves or killed.
When the people heard there heard Juan they suddenly felt thankful to Sun Alliance for arriving on their planet otherwise who knows what could've become the fate of this planet?