25-30 years ago, they would have started the race. Even in 1997, they did a few laps behind the safety car and then let them go.
They probably would have still done a half-points race and it might have been somewhat farcical like 1991 Adelaide, but who knows? I think knowing how treacherous Eau Rouge and Radillion could be in the wet, they had to make these decisions.
Really just should have run it the next day, since the logistics of going to Zandvoort weren't going to be greatly affected (as opposed to the 24-hour disruption caused by flying out the teams and equipment halfway around the globe).