in D&C 89 to what is now a commandment for Latter-day Saints. I really don't see the distinction you're trying to draw here anyway. It would be a sin for me to drink a beer after work today. Is it a sin for non-baptized people? I don't think so. Is taking care of people more important? I think so.
However, it's important enough that drinking a beer would keep me out of the temple (not for long I suspect). It was also important enough for Pres. Monson to emphasize it in the most recent General Conference. And you'd have to ignore the teachings of probably every prophet going back to at least Heber J. Grant to say that it is not an important commandment for members today.