I can't find any official statement about it but due to this Forbes India it seems to be due to Kamat.

Kamat is an old hand in the Indian television space. He started his career with Star TV in India as its senior vice president in 2004, where he worked along with Dhar.........

In 2006, Kamat got an offer to join Endemol and start Endemol India. He shared his plans of moving on with Nair. “I told Rajesh [Kamat] that he should take Deepak [Dhar] along with him. ‘While you look at the business, you will need a creative person to manage the shows', I had told Kamat then,” recounts Nair, who is now the group CEO of Balaji Telefilms.

That year, Kamat and Dhar started Endemol India (the company changed its name to Endemol Shine India in 2015) in a small office in Andheri. In the first week itself, Kamat walked over to Dhar and gave him CDs of the Big Brother show, the flagship show of Endemol which had become a global hit. He told Dhar to see if it can be adapted to India. Dhar realised the show had explicit content that would not be palatable to the Indian audience. He started reimagining the concept.

He decided the show would need celebrities. He and Kamat pitched the idea successfully at Sony Entertainment Television. Film actor Arshad Warsi was the host of the first season which was won by yesteryear actor Rahul Roy.

In 2008, Kamat moved to Viacom18 to start a new general entertainment channel called Colors and Dhar became the managing director of Endemol India. From its next season, Bigg Boss moved to Colors.

Kamat left to join CA Media in 2011 and Nayak took over as the CEO of Colors. “Bigg Boss is a complex and expensive show,” Nayak tells Forbes India.

So show was always endemol show and when Kamat switched the team he took the show with him.

I can't find any official statement about it but due to this Forbes India it seems to be due to Kamat.

Kamat is an old hand in the Indian television space. He started his career with Star TV in India as its senior vice president in 2004, where he worked along with Dhar.........

In 2006, Kamat got an offer to join Endemol and start Endemol India. He shared his plans of moving on with Nair. “I told Rajesh [Kamat] that he should take Deepak [Dhar] along with him. ‘While you look at the business, you will need a creative person to manage the shows', I had told Kamat then,” recounts Nair, who is now the group CEO of Balaji Telefilms.

That year, Kamat and Dhar started Endemol India (the company changed its name to Endemol Shine India in 2015) in a small office in Andheri. In the first week itself, Kamat walked over to Dhar and gave him CDs of the Big Brother show, the flagship show of Endemol which had become a global hit. He told Dhar to see if it can be adapted to India. Dhar realised the show had explicit content that would not be palatable to the Indian audience. He started reimagining the concept.

He decided the show would need celebrities. He and Kamat pitched the idea successfully at Sony Entertainment Television. Film actor Arshad Warsi was the host of the first season which was won by yesteryear actor Rahul Roy.

In 2008, Kamat moved to Viacom18 to start a new general entertainment channel called Colors and Dhar became the managing director of Endemol India. From its next season, Bigg Boss moved to Colors.

Kamat left to join CA Media in 2011 and Nayak took over as the CEO of Colors. “Bigg Boss is a complex and expensive show,” Nayak tells Forbes India.

So the show was always Endemol show and when Kamat switched the team he took the show with him.