One of my favorite CS Lewis novels is Out of the Silent Planet. I think it even used the word “quarantine” to describe why God would not allow the angels—oyarsa (sic?) in the story—were not allowed to visit the earth: it was the domain of Lucifer. I remember that the Bible says God cast Lucifer out of Heaven for rebelling against God. That’s what occurred to me after I reread your post and prompted my question.
Too me, being a quarantined planet answers so many of my questions. I also see it as protective for us.
If Satan and his angels assume the identify of a planetary federation organization, we know by default that it is probably a deception.