BB did not want Abhinav at all. They actually supported Rahul and expected him to fight till the finish. He suffered from a burnout and gave up to non existing competition. In short allowed Abhinav to take his place.
Salman Khan did not roast him out of the blue. He did it with the intention of showing Rahul his own mistake.
In the promo Rahul looks puke worthy. I am sure he had more votes than Jasmin but in the meantime BB saw another potential Ruby vs Abhinav and Jasmin vs Ejaz. Rahul ka pata cut gya
Rahul himself made way for his own exit by not giving his 100% in the task.