Correlation is definitely not evidence for causation. Also, if you reverse the cause and effect, what analysis do you get? When BTC prices are in the rise, it’s because people are putting money into crypto currencies. When people are putting money into crypto, some of that money is probably going into tether, so there’s more demand for tether, so Bitfinex increases the supply. With this reasoning, we get exactly the same graph with a totally different meaning.