Since Villin knew that nobody was controlling the mind currently and he was only going up against the mind's natural instinct to protect itself, he decided to take his time. The wall in the previous region of defenses wouldn't repair itself without himself or Ashera making it so.
"Now, what to do here…"
Even though Villin had already made a plan before going on this trip, he was getting a bunch of different thoughts and creating different plans while he was actually there trying to attack. He decided that if he got out without a problem, he could attack his mind again in the future to find potential weaknesses.
The initial plan was to create a blimp. The stone soldiers wouldn't attack him which only leaves behind the stone wyverns. Since the mind was purely going off of instinct it wouldn't realize the blimp was the real threat and the wyverns should all go for Villin instead of the balloon.