The prize is calculated as the equilibrium of the top 20 exchanges by volume. Just throwing in a 1000 BTC bid or ask on one or even five exchanges at the same time does not change or manipulate the price whatsoever.

To have the price of BTC jump a few thousand Points in a short amount of time, you would need to throw in market orders like 30-60 Billion $ spread across the top exchanges, accepting any ask price... That would be manipulation.