By September, Twitter will have to be in line with tough new European rules governing—among other things—online disinformation. It will have to demonstrate how it’s fighting disinformation on its service and, if it fails, it could be fined up to 6% of global revenues. We know this is all good with CEO Elon Musk, because the man himself said last May that the incoming Digital Services Act (DSA) was “exactly aligned” with his thinking. So Musk must be terribly disappointed to see that his company has flunked its first EU disinformation test. Last year, all the big social media firms...