To take advantage of this situation you just have to long BTC and short XRP with the same ammount, creating a hedged strategy. If BTC crashes XRP will crash even more, and if BTC keeps going up, XRP will not keep up because of the SEC action against ripple. The only scenario where you loose is if XRP goes up when BTC is crashing, an impossible one. The potential downside is limited and the upside is very large with all the money flowing from XRP to safer BTC.