I was bit by this exact same tactic early this summer, May or June, when Ripple shot up. Bought some, decided I wanted out, and Polo went down until I could only get out at a loss, rather than the considerable profit I had seen in 20 minutes or so (I forget exactly, it was up 25% or more though).
Not doing business with Polo any longer.
Well, wasn't exactly the same tactic; you're discussing them turning off deposits rather than turning off the entire site. Same basic disgusting ugly source though (greed, to the point of overcoming fair dealing).