The problem is two-fold. On one hand, there seem to be some empirical evidence that might indicate that people whose predominant racio-ethic background is X might tend to have certain bodily characteristics such as longer or shorter legs, etc. On the other hand, since WWII and the Civil Rights Movements since the 50s and 60s have drilled it into us (quite correctly I think) that race is largely a social construct that has been primarily used as a way for one group to establish spurious dominance over another one, usually through violence and cultural erasure. The problem is that this seems to be working. It sounds as though they are already asking things that would be indicators of waist size and such but that the racial component gives them a better sense of proportions people generally don’t know.