Rinosus was also shocked by the enormous pressure emitted by Nova. 'He wasn't this strong back then!'
This meant that Nova became so strong in such a short time. Thing that made Rinosus doubt life, because it should've been impossible for a being to advance so much, anf so quickly at that.
"Umm, Master Nova... You're not really going to?" Rinosus couldn't help but ask this, as it seemed that Nova was going to face-off against Dixon's Master.
When he heard that, Nova didn't stop at all as he said, "Continue with the plan. It's just that I'm not going to be part of it."
This meant that Nova decided to go separately against the Demon Region, he didn't wish to implicate Rinosus and the others anymore.
It was in the spur of the moment that he took this decision.
If he failed, then the fact that Rinosus helped him would surely get the latter killed, not to mention his family, friends, or even subordinates.