Made no sense

Why did the DEA agent guy want 50 cent to work for him. I know all the people 50 cent killed were bad people but he tricked him into helping 50 cent get his revenge. I know he probably wanted him to get to the head guy Gabriel Baez but how can he trust 50 cent not to kill him too? From what I could remember even though Sarcone killed his father I think Baez order the hit when he found out Mal's dad was a snitch.

The world is quiet here.