Capítulo 1853: The Blue And Green Rock.

They are not doing this so that they can gain access to God's Domain and install their own puppet for it to get them the Authority of the void universe. They plan to attack God's Domain and directly steal the Authorities within it for themselves with force instead of going through the complicated process that others are doing. 

They don't plan to jump through hoops after going through so much effort to find his world. It is a good plan. But it is not a plan that will catch the God of Power off guard.

He has been aware of their plans to invade his realm right from day one when they tried to break through the encrypted defenses of the pillars that connect to his world.

It was not surprising to him that that's what they chose to do because that's the only thing they can do to harm him. He has reduced the avenue of their attacks to the pillar he distributed, so they have no choice but to try and crack the pillar in order to invade his world.