Proof they're lying about audits should be strong evidence the 1:1 dollar backing is an unreliable claim at best.
Unreliable claims to $2B in assets should be treated as extremely suspect until a reputable audit is provided. "I've got a Canadian girlfriend you've never met" doesn't fly in middle school; it shouldn't fly in a financial system.
Tether's claim now is more like: "There was a girl in my apartment on June 1st. Our lawyers are pretty sure of that, but not sure enough to claim anything else."