...
What do you mean by 'in the Tether reserves'? Surely all USD they hold in bank accounts must have been deposited as USD. If you mean people having Tether wallets or holding Tether on exchanges isn't that then like arguing that the Federal Reserve is at fault if funds from dubious sources are held in $100 bills?
...
I´m not sure if that is sufficient proof for you, but you should read this
reddit post by bfx_drew:

The bolded part of your post would be wrong if this is indeed true.
The source of funds could potentially be a problem, because unlike the Federal
Reserve Tether could be shutdown by US authorities (some people already are
comparing Tether to LibertyReserve, which was eventually shutdown after years
of operation).
...
Edit: I think I've worked out why they took that off the website. Now Bitfinex requires verification to be able to withdraw USDT. Did they not require it before?
...
I´m not sure. I´ve only deposited BTC into Bitfinex and all my withdrawals
were made in Bitcoin, too.