Michael the archangel is not a saint because he never had to be sanctified.
He never fell into sin.
Thtat’s why we don’t call him saint.
St. Michael is called a Saint by Roman and Eastern Catholics, Coptics, Anglicans, Episcopals, and Lutherans, leaving you in a very distinct minority of those who call themselves Christians. That causes me to ask who exactly is "we"?
Peace be with you.