Then they would never catch up with the SC.
There are solutions for that. For example: At a SC situation, all drivers proceed with 50kmh to the start and finish straight and are being instructed by race control where they are not allowed to warm up the car by weaving and such and eyeball what is safe to do. At 50kmh this is something even an 80yo grandma could do. Then if they are passed the incident, they proceed down the rest of the lap with 50kmh and bunch up on the starting positions in the order you arrive with the race leader standing on the Pole Position. If the last driver is standing still, the drivers may follow the SC which is waiting at pit exit. SC dictates the speed that is allowed to be driven, like it is now. Drivers will be told again which sector/corners they are not allowed to weave or warm up the car. During the SC period when the recovery has been completed, the lapped drivers may overtake, in a similar fashion to now, before the SC ending period and the race again commences.
This all will significantly take down the amount of time it costs to catch up with the SC, like how it is nowadays, even with an imposed 50kmh limit. It also will secure the safety of both drivers and marshalls. And it will allow for a faster deploy of the marshalls and/or recovery vehicles and thus the SC period taking less time and/or laps to complete so we get to see more laps of racing.