Been a while but last time I had to deal with one, I put the drill onto it, then canted off axis, in hopes of the bit center going off center and the rivet not being able to keep up with the drill speed.
Maybe peen it down, see if can be deformed enough into the deck that it might not spin? Can you access both sides? Maybe cold chisel and work at it?
Does part #9 thread into it? If you put it back to together, then hit it with a fast moving impact, does it tighten up fully? Not sure what that would accomplish, but sometimes in the act of gorilla'ing something, I try different things, until I succeed. Maybe if you put the wheel back on, sans some washers or with extra ones, you can lock up the works, then gain leverage to try to bend it apart.
Have you tried a hammer? [only half joking]