Earlier quoted context omitted.
If tether is pumping BTC then it’ll stop pumping BTC when it’s taken away. Weak hands will fold and then there will be a crash
OK, yes, that's a fair point. But it's not clear to me that pumping being taken away would be a bigger change than people trying to get out of USDT and buying BTC. Also we've been there (mtgox's willy etc). I don't think bitcoin will be much less volatile any time soon. https://www.youtube.com/watch?v=XbZ8zDpX2Mg
People trying to get out of USDT into BTC because the USDT:USD parity assumption collapses will boost BTC:USDT prices, but probably not enough to avoid dropping BTC:USD, because it would be less than the USDT:USD drop, is the idea.