Her concerns were very valid and sound.
There were extremely few Martial Seniors at the very highest echelons of the Senior Realm who could overcome the things that Rui would be subjecting himself to.
"My rationale is sound," Rui replied calmly. "I am strong. Far, far stronger than I was when I was training under you five years ago."
"I can see that," Master Reina remarked. "Your progress is truly astounding. I'm just cautioning you not to let it impede your judgment."
"I understand. I am doing my best to ensure that it isn't and hasn't while in regards to this decision," Rui replied with a composed tone. "My primary goal is to survive; my secondary goal is to eliminate the threat to me; I can do that by suppressing them with blackmail or even killing them then and there if I can get away with it. Thus, my goal is to exit this ordeal with the threat eliminated and no loss of quality of life where I have to be constantly protected by the Martial Union surrendering my agency."