In a recent article, the Economist argues that regulators should treat Tether like a bank. Would you agree?

Yes, Tether and the connected exchange Bitfinex were buying BTC with USDT when there was a bear run to push back the price up. This injection of liquidity in the Market is typical for central banks. That’s why people think that Tether should be regulated as a bank. Also Tether creates and redeems Tether itself, also similar to a (central) bank.