Tether did defraud people. They lied on their website, claiming a) audits (which they never completed a single one of) and b) 1:1 backing of each Tether with a dollar in the bank (which they didn't have).
So I guess its ok. Might as well pack it up and let them carry on with manipulation, lying and profiting. I don't get your rationale whatsoever.
Despite their lies, they were apparently able to meet their obligation to exchange tether for dollars for everyone who wanted it.