Surely a safety car caution should immediately freeze the field and determine the restart order of the drivers no matter what happens during the safety car caution with respect to pit stops.
The Webber incident was unusual in that the SC was called even before the accident stopped happening. Usually there is somewhat of a delay before it is called, as Charlie checks to see exactly how much debris is on the track, where all the cars are, if cranes are nearby etc...
So your proposed typical scenario would normally be
1. Incident occurs.
2. Teams who are nearly due a pitstop anyway call cars in.
3. Some cars enter pitlane to get new tyres.
4. Safety car is called, pitlane gets closed.
5. Somewhat later, the cars who pitted (who now have new tyres) are reworked back up the field to where they were originally. A free pitstop.
No matter what rules you put in place, there will ALWAYS be winners and losers. Some people just dont get this basic fact.