Su Yu used the authentic Buddhist Law to transform the hatred and murderous intent in his heart, which was actually not a bad thing for Wu Chengzhi. After all, if he were truly overwhelmed by the hatred from the extermination of his clan, Wu Chengzhi would only have two outcomes: either becoming demonized in his quest for revenge, or falling into demonic obstacles and becoming a slave to his murderous hatred and resentment.
No matter which one.
The chances of him actually taking revenge for the Wu Family were slim.
On the contrary.
Being transformed by Su Yu and used by him.
He might have an unlimited future ahead of him, and becoming a Dao Master of the Hollow Void Realm was not an impossible dream.
As for revenge—
If Su Yu really took down the Butu Buddha Gate and then used the Molo Great Vajra Sutra for physical transformation and the Earth Treasury Undying Sutra for spiritual transformation.
In fact, that could also be considered a way of avenging the Wu Family.