Great info.Correct. There was a CM stationed at the 7DM entrance politely informing folks that "The park is not opened yet". We asked if she knew when we could ride 7DM and all she would tell us is that we could ride it once the park opens. We got on the ride well ahead of the first wave of rope droppers arrived and that's all I really wanted/expected.
EDIT: I'll add that I don't know if they've stopped letting folks ride 7DM prior to park opening altogether. That's just how it worked the day we were there.
Even if they do stop the early rides that allowed 2 or 3 trips through the mine,being allowed the one ride ahead of everybody else is still a really good "perk".