It will be interesting to see if thats the case when it rains heavily anywhere else. Somehow I can't see them continuing. Say Spa.
As shown in q1 and q2 it is only stopped if you get enough standing water. At that point the cars start aquaplaning regardless of speed. At the point they can't even follow a SC there is no point continuing. Normal prolonged rain at nearly any other circuit would continue.
These also are not the cars from 1996, far more reliance on aero grip which is not generated at low speed. Less driver aids and so on.