I feel your anger. I was there today and got a total of 7 rides in. 3 on Skull Mountain, 1 on Dark Knight, and 3 on El Toro. I was still riding on El Toro when I was told that the park was closing and had to get off.
I think the park closed more for the poor turnout than it did for the weather as it looked to be getting better when I left. I just checked the weather and found that its not raining there now, so the only explanation for closing would be the poor turnout. Oh well, what did you expect? Its Six Flags.