For what legal terms?

The moment those coins got listed in Poloniex, devs are truly aware that Poloniex is delisting coins once it doesn't reached the required trading volume in a certain given period of time. In that case, "average trading volume for the last month has not exceeded 0.2 BTC/day (6 BTC for last 30 days)".

That's one of the reason why I preferred doing altcoin trades at Poloniex.