I do remember Tela Vasir saying that she had taken the job from her Shadow Broker contact, and that she had no problem making people disappear to protect the Shadow Broker as she has always gotten good info from the Shadow Broker. This had nothing to do with the Council making a decision.
I do not think Vasir planned to go rogue. I do think she made several mistakes. This job was extremely botched.
Mistake 1: When Vasir attempted to assasinate Liara, she missed. Liara evaded Vasir for 4 minutes while she left a message for Shepard. Then Liara was able to double back to put eyes on Vasir.
Mistake 2: When Shepard arrived on scene Vasir merely sought more information about where to find Liara. She never asked Shepard why he was operating in the area even though she clearly knew of Shepard. In fact, she misled Shepard into thinking she was there to investigate the murder attempt on Liara.
Mistake 3: Contacted the Shadow Broker Troops, letting them know the intended targets will be at the Drakon Office Building. The SB Troopes blow up 3 floors and still miss both Secat and Liara. Vasir later complains about the sloppiness of the work.
Mistake 4: Liara shows up at Drakon and identifies Vasir as the would-be assassin. Vasir panics, diving through a window to escape using biotics to slow her fall. Shepard catches Vasir on the way through the window but looses his grip about half way down. Shepard bounces nicely off the pavement.
Mistake 5: Liara stays on her so Vasir tries to escape in a sky car. Piloting wrecklessly, Vasir causes a lot of sky vehicles to crash. In addition, Vasir drops several military grade mines into traffic lanes before Shepard catches her and causes Vasir to hit an oncoming skycar nose on. Vasir is injured in the strike, and crashes on the roof of the Azure Building.
Mistake 6: As Vasir panics further, she becomes more dependant on the SB Troops. The SB Troops are no match and only succeed in creating more death and mayhem by shooting up the town.
Mistake 7: Vasir grabs a hostage. Not exactly what the council envisioned as the actions of a Spectre.
Mistake 8: Fighting the final battle injured. Did Vasir not believe in the use of medigel? If she was fighting that way hurt, think of what she would have been like healthy. Omg...
Mistake 9: Vasir is more concerned about Shepard the Cerberus agent judging her than getting any help Shepard might offer.