The point is that this wasn't considered, even though it's entirely possible with Kuma's power. He wouldn't need to risk a single life.
Furthermore, given the low level of information they have about the World Government (Dragon didn't even know who Imu was), why didn't Dragon participate in the operation at the Reverie? His Zaza power could have been useful for creating a powerful distraction for an escape in case the mission failed.
The entire construction of Dragon has a purpose that is not fulfilled, just like Oden, whose purpose was an attempt to construct a heroic myth that confronts the evil that oppresses the weak, but which in practice translates into a figure who makes flawed decisions that prolong the suffering of the oppressed.
In my view, if Dragon possesses this power that is the Celestial Dragons' weakness, it will further expose this flaw in the character's execution. The more resources he failed to use over time that are added to his arsenal, the worse it becomes for his reputation, especially if he always had this power, as theorized by those who believe he was the one who helped Roger escape from Shiki's crew.