True enough, but starting at 9:00 AM instead of 7:30 AM still leaves plenty of time for that. It wouldn't have been enough for me, but an extra hour and half of sleep would have been way better than nothing.
I also suspect that starting at 11 AM-1 PM and going until 4-5 PM, despite being less overall time, would produce vastly better academic outcomes in high school just due to the average teenage circadian rhythm and the resulting zombification of current students. The noneducational duties of high school could be handled by letting students show up earlier as needed with breakfast/lunch provided- the structured classes would just start later.
Maybe give the early arrivers a place to take a nap while we're at it.