>Every piece of market news that says "market change X, because incident Y" is pure speculation since there is no way to establish Y as the cause.

This is not correct. There are many market news items that can be directly attributed to another event. Boeing's numbers this week are directly attributable to the Max fiasco. The company and analysts agree on this. Why would you assert that it's "pure speculation."

I mean, he's right that correlation =/= causation, but you're definitely right that there's a lot of times the link between the two are pretty obvious

Fair, if it's a specific stock and a specific event affecting that company, I don't have so much of a quibble with that (although it could still well be that 0.2 of that selloff is because of the event and the remaining 0.8 is because the first 0.2 sold.)

I'm more thinking of the "Markets are down 1% today because of uncertainty associated with the China trade"-style reports.