Sunil is an ardent advocate of ending prejudices against dark skin in India. In a powerful essay in 2019, Sunil wrote: "As a young teen growing up in India it was sort of a foregone conclusion that if you were fairer you were prettier. I was a sports kid growing up and my schedule involved training as a swimmer for five hours a day, six days a week. I was a very tanned dark kid. My mum, who was very dark-skinned, much darker than me, constantly drummed into me that I was beautiful. It must have worked because if I had just my high school teenage experiences for context I would definitely have a complex about my skin. But, as I mentioned, my nickname in high school was Kaalia the crow."