Judges do not make those decisions lightly, they do everything they can not to have to, and there are a number of factors that bring them to said decision. Mumford has been running with eight dogs for several days now, and with only being at the halfway point that was most likely a concern by the judges. Teams must finish with no fewer than five dogs in Harness in Nome, and with still 500 miles to go, if some dogs were showing tiredness or soreness in Grayling, judges may have felt it was too much to ask. (This is just one possible explanation, this in no way is what is known to be the reason IF the musher was asked to scratch at all.)
Mumford was not the last musher on the trail, there were two other mushers behind him. Sydnie Bahl is currently in Grayling and Quince Mountain is on his way to the checkpoint. It's another thing race judges are looking at - if the "stragglers" get too far behind, they are encouraged to speed it up (suggesting dogs don't need 8 hours at every rest stop, for example).
Mumford had eight dogs in harness all in good health, according to the statement.
