Jesus! If that were us at Summit Point (I cornerwork), the red flag would have been out once he lowsided and couldn't clear the track. I had a similar thing happen two weeks ago. But CWs do not go on the racing line until we can clear the bikes or we have an "all clear" signal from our flagging towers. No need to add ourselves to the carnage.
In the list of five priorities of safety for a cornerworker, the first two are 1) Your own ass and 2) Your buddies ass. #3 are the riders still racing (you don't want to add them to the mess), #4 is the downed rider and #5 is the downed bike. It that order of priority until a safe circuit can be established.
I saw and helped clean up 7 wrecks in a single 6 hour period. It's amazing these guys walk away from some of this stuff.