He was a misanthrope, not strictly a misogynist.
He plotted to kill his half-brother because he figured him to be already more popular. He plotted to kill his male roommates. He plotted to ram his car into as many people (male and female) that he could take out before killing himself.
He also plotted to kill his step mother. The young man had severe mental health problems. He came from a broken bitter home. Those characteristics are not misogyny