I suppose it's possible, but holding all else equal? I don't immediately see why dollar demand would increase in the event of a tether collapse.

Dollar prices will adjust as BTC->Dollar and Dollar->BTC flows change. Dually the Tether prices. The only thing that keeps these prices in line is a Tether/Dollar arbitrage, but that arbitrage will slow and halt as people flee tether.

If anything, I would guess that a sudden increase in selling pressure from people doing Tether->Crypto->Dollar risks pushing people into a Crypto->Dollar fear feedback loop.