The report I read in a German language magazine stated clearly that there was no safety car on the track, the crash was cleared up with waved double yellow flags out, which means the track may be partially blocked and all drivers entering the area should be able to stop at any time.
If those flags were clearly visible, which I have no reason to doubt, the speed the drivers are taking through this passage would still have been too high.
Since it’s a junior series with young, inexperienced pilots, I’d recommend deploying a safety car if you need to place a support vehicle on the track, though, precisely because you cannot risk any of these guys getting it wrong, misjudging the conditions or failing to pay attention to the flags and causing an accident.
There was, apparently, a second incident, which is not shown in the video, where a car hit the vehicle more significantly.