The reason why Su Mo wanted to break through to the Rank 2 Empty God Realm was driven by another reason.
After cultivating the Immortal Chaotic Body, it would be easier for Su Mo to break through to the Rank 2 Empty God Realm.
The Rank 2 Realm was known as the Reborn Rank. This meant that his bones, body, Sacred Elixir, Spiritual Soul and Blood Force would merge together to reinforce his physical body.
As such, once his Immortal Chaotic Body was cultivated, it would be very easy for his physical body to reach the Rank 2 Empty God Realm.
That was because the cultivation for the Rank 2 Realm was replaced by the Immortal Body.
In other words, Su Mo had already gone through the rebirth phase. While others had created powerful spiritual bodies for themselves, Su Mo used the Immortal Chaotic Body.