And the author of the article can't.
"Ubuntu has approximately 135,000 instances. In second place, a long, long way back, you'll find Amazon's own Amazon Linux Amazon Machine Image (AMI), with 54,000. Lagging even farther behind, there's Windows with 17,600 instances. In fourth and fifth place, you'll find CentOS, 8,500, and Red Hat Enterprise Linux (RHEL), 5,600."
There are 220,700 instances accounted for, and Ubuntu has a 61% share among those. As other smaller OSs are accounted for, the Ubuntu share only decreases. In other words, it's plainly NOT twice as popular as the rest put together. If I can make as assumption, I think he probably meant that it was "as popular as all others put together." That seems closer to reality.