I am saying this based on a case that happened with Ranbaxy few years back. One of the employees found out the data of the drugs submitted to the regulatory authorities had been falsified and also that the manufacturing process used was sloppy (i.e. GMP was not followed). His superiors did not pay any heed to his evidence and instead was accused of watching po*nography on his company computer and thus he had to resign from his job. Later, he made a complaint in US under the False Claims Act (as the company was selling drugs in US), also called whistleblower's law wherein any individual can file case against the government contractors for submitting fraudulent claims to the government. The company pleaded guilty and was fined a heavy sum of compensation. But as far as I know the information regarding where is he living was never ever disclosed...
So, SK might have called Kabir to disclose information about the wrongdoings of the company. He was indeed a whistleblower in this case. Most of these people generally end up being harassed, threatened, forced to resign or even murdered. So murder does seem a plausible option in this case. But, since his body has not been discovered so is there any chance that SK is alive but staying away from his family in order to protect them and maybe now working as anonymous health activist (because the whistleblower protection bill in India does not address corruption in private and corporate sector)? Plus, the pharma sponsor case is also there which I am pretty sure will land KKN in trouble ( let's assume it's about wrongful marketing of drugs) and we can hope SK's case to come forward when this happens.