Nobody here wonders WHY IN HELL would aliens be HIGHEST clas? Higher than sick pedos and programs to enslave an entire planet ?
It could mean, disclosure would jeopardize ALL the rest?
I'll give my take : It's about what is hidden in antarctica?
Someone parked here long ago, or had to move its ship because fist parking place was sinking in the ocean?
That wouldn't suffice for "highest clas".
Except if something of huge interest is in it…
Something that can talk and has an advanced knowledge on how to keep a planet under control…
That would explain also why DS playbook's lack of flexibility since strings were cut…