Earlier quoted context omitted.
You can fork BTC to do whatever you want, but it doesn't come with liquidity. In other words, a fork doesn't come with the same amount of inertia.
Suppose BTC is met with a severe logjam as predicted by the author, won't a solution that does not involve mass liquidation (for e.g. a fork) be in demand and eagerly welcomed by existing BTC users?
That, of course, would not happen. Even if there were such an event you'd still see people trying to beat the clock and mass liquidate the old BTC while there's still demand, or people immediately liquidating their positions in "new BTC" because they think it's not going to eclipse "old BTC".
We have a good real world example of these very things happening with things like BCH and Ethereum Classic still trading quite regularly. Both were the result of some users deciding to move to a fork and some deciding to stay. In traditional markets you could make some parallels with a stock split or demerger.