Also, I've been watching the exchange price action closely. Coinbase/GDAX has been leading Bitfinex significantly during upward spikes, suggesting that it isn't Tether that's pumping the price. And if you look at Tether's circulating supply, it's silly to think it could singlehandedly prop up the entire market.
I don't really see what is silly about that, it's just "Willy MtGox" all over again. And it's even easier in this case, not only they own the Exchange (BitFinex), they also own the "Fiat" (Tether).