Throwing chairs and spitting are not normal behavior for that age. Four year olds know better, or should, and I wouldn’t have tolerated allowing my child to be around a kid like the ones in the mother’s column.
The school had to do something to protect the other children, and frankly, I’m surprised that these kids were allowed back a total of eight times. My daughter’s church-based, twice a week,half-day preschool would have and did expel kids for less.
Granted there really are some bad seeds out there. Aside from them, I just find the concepts of formal suspensions or expulsions for preschoolers, as a general rule, a bit over the top.