We have ZERO context on why the govern didint try to catch luffy before with ALL their strenght. So judge that is straight up Dumb.
Shanks could be the One that told them, and they only know It since the reverie, or Im told them Just now, also in the reverie....
We dont even know YET If the gourosei fear the fruit itself, that has some special abilitie or the one that had It before...joyboy.
And since was joyboy that had this fruit, they afraid the next one will cause the same amount of problems for the govern, and the fruit itself dont have any special abilitie that they particulary fear, Just belonged to their main enemy.
We Will have WAIT. Dont judge like some retards do here without any context.