From my own personal experience people of the same ethnic complexion and religious views as Greg would be called "Towelhead" and "Sand Nigger".
In speaking with an Urdu speaker and Baha'is practioner I found that "towelhead" is appropriate. He explained that Sikhs in his opinion are a blending of Arabs and Hindi's. He said the blend is odd because historically the two groups have been at odds. He said that the neighborhood determines the acceptance and tolerance of the mingling. Arabs and Sikhs in a Sikh neighborhood is completely acceptable and the same is true in an Arab neighborhood. A Hindi and a Sikh in a Sikh neighborhood is accepted but a the same couple in a Hindi area is viewed as more cautious. The men may joke and tell others to "lock up their wives".
Free speech in India is comparable to the US and other Western States. Greg could not recount any specific cases of hate speech in Indian culture.