Wrong
Shah Rukh Khan was offered Dhanush's role in Shamitabh. In fact, the film's title came from the acronym of Shah Rukh Khan and Amitabh Bachchan. But things didn't work out and Dhanush eventually landed the role. Director R Balki came up with the idea for Shamitabh when he was stuck in traffic while on his way to the senior Bachchan's 69th birthday bash.

Correct
Shah Rukh Khan was offered Dhanush's role in Shamitabh. In fact, the film's title came from the acronym of Shah Rukh Khan and Amitabh Bachchan. But things didn't work out and Dhanush eventually landed the role. Director R Balki came up with the idea for Shamitabh when he was stuck in traffic while on his way to the senior Bachchan's 69th birthday bash.