If you were correct that BlackRock was not holding silver and falsely reporting that they did, that would for sure be a federal crime and would risk a run on the trust. It would likely generate sudden demand for silver as well, since the ETF operator would be liable to cover its liability.
However, since you are speculating about a crime of which there is no evidence your claims of market abuse can be disregarded. (And if you had any evidence I can assure you that the SEC would like to know. You can contact them here:
http://www.sec.gov/complaint/tipscomplaint.shtml )
I understood your objection to ETFs to be the existence of synthetic longs and shorts, and that you claimed that these somehow manipulated the (spot/future/both) price down. It seems not, in which case as far as I am concerned, you're not making a case that the silver price is manipulated by ETFs at all.
(You still should oppose any and all synthetic derivative positions on principle though, assuming you are opposed to fractional bank reserves)