I am trying to understand.
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If the goal was to get USDT, you could have done it at eXch, which does not segregate funds.
Perhaps at the time when he wanted to exchange his bitcoin, eXch didn't have any USDT in their reserves or not the amount he wanted. It has happened to me in the past. Alternatively, he could have swapped his bitcoin for DAI or USDC. If stablecoins weren't available at the time, he got the next-best thing, ether. With ether, he can buy the stablecoin he wants at Uniswap, which doesn't support bitcoin, only bitcoin-wrapped tokens.
I didn't discredit any platform. I'm just a newbie. But I'm not here to discredit Exch. I used Bitcoin to exchange Monero and ETH, and then used Exch to exchange ETH again. Then I sent it to Uniswap. Then I used Uniswap to exchange USDT and sent it to my own Bitget APP. But my Bitget account was indeed blocked. I sent the address before. You can check it. I didn't lie.