At which point Bitrex says Alice can go fuck herself and locks her account. I think you are grasping at straws here if your argument is that this actually gives Alice an advantage when the reality is that it would be a fucking nightmare if 3/5 mining pools decided to fuck your wallet over.

I'm still leaning heavily in the direction that @Dan is right. The only counter arguments I can see is the likelihood this would happen. Which is pointless. WE KNOW IT CAN HAPPEN. Its functionally possible. But the moment Bitrex starts losing money to double spending is the moment shit gets locked down fast as fuck with them.