Most of US economy isn’t productive manufacturing output, it’s stuff like service industry, software shops, financial economy, etc. Some of it, such as the health insurance industry, is actively harmful to society. There’s a great article explaining how US lost most of its productive economy at this point.

https://americanaffairsjournal.org/2021/08/the-value-of-nothing-capital-versus-growth/

Industrial output in US accounts for something like 15% of the overall economy, and steel production levels are comparable to Russia. That’s a pretty good proxy for the size of industry in a country. So, when you compare US military spending to the productive economy in the country, then it’s a very high percentage of the industrial GDP.

Also, the article you linked counts all the military adjacent economy to get to the 10% number, US military spending would also look a lot higher if we did that. US defense spending is currently well over $1 trillion a year.

https://www.thenation.com/article/archive/tom-dispatch-america-defense-budget-bigger-than-you-think/

Meanwhile, US industrial output is around $2 trillion.

https://www.brookings.edu/research/global-manufacturing-scorecard-how-the-us-compares-to-18-other-nations/