I agree with you that the original premise of Polo being in on the wash trading is unlikely, but I wasn't suggesting that at all.
You actually believe the Eth wash trader is paying 100-200 BTC per day (sometimes probably even more than that) just to wash trade? It's obvious Poloniex has made a backroom deal with them because they'd be better off just buying the actual coin to manipulate the market rather than wash trading if they were paying that much.