From the perspective of the Holy Nation, it was Minister Drost who poisoned the Queen Consort, and the rebellion in Avalon was initiated from within by the ministers. Although Star Antimony stirred the unrest in secret, they did not directly attack the Queen Consort, nor did they pursue Isabel, therefore not crossing the red line of the Holy Nation.
Furthermore, the people of Avalon at that time highly approved of the puppet Queen Isabel, for she brought "peace" — after realizing the strength and ferocity of Star Antimony, the hard-won peace was all the more cherished, and even though the puppet Isabel was constantly funneling various benefits to Star Antimony, eliciting dissatisfaction, no one dared to oppose her.
——After all, Star Antimony had truly terrified them.
Even with the signing of one unequal treaty after another, draining Avalon's resources, no one dared to resist Star Antimony. Because Avalon had been disarmed, and resistance seemed futile.