I'm not a big Vox fan, but the article you linked doesn't explain why they were using a Gmail account. The Nat. Archive handled the archiving of the Obama Admin

I'm not a big Vox fan, but the article you linked doesn't explain why they were using a Gmail account. The Nat. Archive handled the archiving of the Obama Admin's tweets. They are not in charge of the Trump admin's securing the account once it was handed over.