In my view Sikhs donot belong to any particular race. A Sikh is a Sikh. There is nothing like black/white sikh. Sikhs belong to whole world. So it is a good oppertunity to identify sikhs under other race category. It will impress upon Govt. of U.S.A. to better understand the Sikh community. I think the forms, if Sikhs checks under other category, will be rejected or thrown away. U.S.A. Govt.is free to consider all such cases falling under Asian Indian. In no case this is anty any country in the world.
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/community-out-reach/29566-us-census-2010-sikhs-don-t.html
Reference:: Sikh Philosophy Network http://www.sikhphilosophy.net/showthread.php?t=29566

Regards.

Balbir Singh.