I cannot judge the lyrics that I don’t understand.
He probably do this, as a member of a mendiant order, he probably live in a neighboorhood where the rap culture is predomminent. So he use this canal to express his faith and evangelized.
Rap is a great way to express emotions, idea, feelings, etc. It is a sort of street poetry.
Yet, it is a paradoxal for a monk to use it. First, rap and religion don’t match easily, as this sort of music is more a way to express relellion. Then it is often practiced by rude men, have explicit sexual connotations and express violence. Exact opposite of what a monk is supposed to be!
So I can understand that some people can find it shoking. I am not completly at ease myself. More, with the Church decorum.