Or they can't prove that they are doing anything wrong, which I actually think the fact that they are still operating likely means that many of the boogie man tether stories are likely fictitious. People use Tether as a fiat proxy where there aren't easily accessible fiat on/off ramps.
At worst it sounds like there may be some fractional banking going on with tether, but the tethers seemed to backed by real dollars eventually either way.
If they weren't doing anything wrong, why was Phil Potter claiming that Bitfinex and Tether are completely separate entities, not related to one another? We only found out the linkage after the Paradise Papers were released. That's pretty much when the "FUD" started.
Btw, Potter resigned from his post @ Bitfinex in June.
Perhaps using a legal or technical definition they are separate entities would be my guess. I am not saying they haven't done anything or aren't, but I am saying that at this point if it was as bad as some seem to think it would have come out for sure by now. They would have hoodwinked a lot of people into buying their tethers, people with a lot of money.