Oh, they are clearly from the lower divisions. Both the wrestlers and the referees dress differently. The totally empty stands are another hint! People don't start to show up in numbers until the top two divisions are fighting.
There are six divisions in professional sumo: Jonokuchi, Jonidan, Sandanme, Makushita, Juryo, and Makuuchi. Only the wrestlers of the top two, Juryo and Makuuchi, receive regular salaries and enjoy all the privileges of rank.
It is salt, yes and the juniors do not have the same privileges that the higher ranked sumo have, they pretty much have to just get on with it. The high rank sumo can hype it up for a max of 4 minutes before they start and throw salt around!