there is no good reason for the rule (open at 9 am at the earliest), and they don't care to explain it
sure, there are times when it has snowed at night, and maybe a plow needs to run up and down the road, and someone from the NPS needs to check that out first. Everyone gets that.
But when it is light at 7 am, and there has been no new snow fall for days, and it is sunny, and the road is bare, and NPS employees are already on duty but refuse to open the gate until 9 because "that's just how it is" is BS