Your stock example is not what was described though.

You're not selling Bitcoin and then buying USDT. You're buying USDT with Bitcoin.

With your stock example, you can't buy shares of Apple stock using your Google stock. It has to go to fiat first which is a taxable event.

And swapping BTC for USDT still a taxable event. Just as if I bartered my Apple stock for some Google stock of yours: for both of us, there's a capital gain or loss, and it's a taxable event. You don't have to go through actual cash money for it to be a taxable event.

https://www.irs.gov/pub/irs-utl/OC-Barteringandtrading-eacht...

Your interpretation of the law was potentially correct before the Tax Cuts and Jobs Act (this was debated but was never taken to court) but is now not correct and crypto-crypto swaps are taxable and you use the dollar value as reference price. This may not be the case in other countries.

But when each Velodyne Lidar share is exchanged for 0.8204 shares of Ouster (in the near future), it won't be a taxable event.

When you sold stock A, you got dollars for it.