Looking up “sauce” in Bob brings back several suggestive results, like

• être au milieu de la sauce for “being in a pickle”
• sauce for a difficult situation

And

Je vais t’arranger le coup

definitely means “I will help you [get rid of this/solve this problem/get what you want]” so your magazine’s translation does sound plausible.

The problem is that, in a blackmail context, you might very well pretend to be “helping” while acting as a go-between to facilitate a payment. That’s apparently what Benzema did and what to think of this is not really a linguistic question.