Racism involves hate. The op was just adding details and not in a derogatory way by using any terms. I'm Asian, and was not offended.

I actually had the guts to ask some lovely SQ FAs this very question (involving silverware though) a few years ago in SIN. They all laughed and smiled (I bet they thought it was me who had been stealing, but it was my uncle...long story) and said that you're not really supposed to take anything from the flight really. Asides from the Magazine or Amenity kit they give you, I guess. So I think taking the blanket was not proper conduct, though if there is any doubt, one should just ask the FA or Purser.