I dont think Becket is in any real power position though. Both Maddox and Smith are dead, whomever killed Smith is still at large and the senator will take his time killing becket. All it has to be is an incident at work and the senator is in the clear.
Becket may now be in a position of no power what-so-ever as all her cards are out on the table and in reality she has none.
Yeah but the Senator can't risk anything.. Beckett did bluff and he probably knows but what if there is the slightest chance something may slip?
The evidence she has was obtained illegally so it wouldn't be of any use in court but if he kills her, it comes to an investigation and someone tips off the investigator and he/she does some digging it becomes official record and usable in court.. and in todays political climate even the hint of wrongdoing (especially when linked to murder) can end careers.
He can't risk that.. he knows she's on the weaker side and that he has little to fear for now so he's content to give it a rest.. for now. What happens in the future nobody knows but as we know Beckett she will not give up.
Very good way of resolving the case while still keeping it on.