The trade here is to be long exchanges that are USDT backed and short exchanges that are USD backed. This ultimately leaves you with a net short of USDT vs USD but it's very different than just being short USDTUSD on an exchange because those very exchanges won't be solvent if this unravels.

So basically if the world doesn't end, you're mostly hedged (you have have manageable spread risk between the two exchanges) and if it implodes, you should see prices on the USDT exchanges skyrocket as people buy crypto to send elsewhere where they will immediately sell for fiat. The result is that BTCUSDT soars and BTCUSD plummets. Now, you'll never get paid on your BTCUSDT length but you will get paid on the short leg in your legitimate USD exchange

At the end of the day there are better ways to make money in life though. But the trader in me will probably put a few quid to work here.