I would contend that it's a new Eternal format, one where if a card was ever banned or restricted in any other format, regardless of whether it was unbanned or unrestricted since, it's permabanned in this new format, which I hereby dub Autoban/Permaban (abbreviated AB/PB).
There are several other examples, just like this one, where a card breaks a format, but is still legal in another format, even though it's still just as broken in that format. Why?!!
Since we can't get the entire playerbase to unite against R&D's bullshittery by refusing to even acknowledge these broken cards (and expecting them to do so will be even less fruitful than attempting to outlive the heat death of the universe), instead, mebbe we should adopt AB/PB as the main format going forward (although, expecting this to happen will be even less fruitful than attempting to convince a trump supporter that the repubilcan party is the reason their life is so shit).
Tl;dr: This mini-column is made of Unrealistic Expectations.