In those conditions, with equipment on the track, the race should have been red-flagged instead of running as a caution. That is something I have had a problem with in F1.
If you have people on the track, disabled cars on or immediately adjacent to the track, throw a full-course caution and slow the cars immediately. Safety first, last, always.
So there’s not been an issue for decades and all of a sudden they should red flag races in the rain in an instance where cars need to be removed from the track? 1997 in Fuji the conditions were far worse when Alono had a much worse accident in the closing stages. No red flag, no major incident, no freak happening.