I'm not sure what the difference is between the excused and unexcused is. I think in the eyes of the state a student is either in school or absent. The parent calling on prevents the child from being accused of skipping school and facing possible punishmnet.
As for calling off school today, I think the superintendent probably made the right call for the overall good of the district. They only get so many days to use. That being said, if a parent like LIG feels it is unsafe, it is their right and duty as a parent to make that determination.