News traveled fast.
In the Myriad Monarch Sect; In the Myriad Monarch Planet; and even the Myriad Monarch Astral Territory, countless transmissions of this event were sent out and learned by numerous individuals! In this astral territory, Factions were widely spread and oftentimes included entire clans, sects, or various other forces. These clan leaders, sect masters, pavilion lords were often considered external disciples, bestowed such a rank and given that classification by the sect's elites.
Such as Wu Jiao.
Therefore, the targets weren't merely those disciples in the sect, on the planet, but inside the entire astral territory.
What's more, due to the hegemonic status of the Myriad Monarch Sect, as long as its foundation isn't damaged or threatened, its pillars such as Heavenly Kings, Commanders, or Prime Imperial Sages weren't targeted, they would essentially allow factions to act as they pleased, and even announce legitimate war.