Is this great to support allies, defend Europe, send a message to China? Of course. These are all great things.
But the point is, it costs the amount of money we're spending. The article is arguing that the money somehow comes back to America. It doesn't. It's not free. All of that production capacity is going to arms manufacture, instead of the economically productive things it would have gone to otherwise. It's not "all upside". It costs something.
If I had a time machine, I'd tell the British, French and Americans to assist the Czechoslovaks against the Germans instead of strongarming them into capitulation. It would have saved millions of lives and trillions of dollars. Many historials believe that without the boost from absorbing the Czechoslovak military, it would not have been possible to blitzkreig across France and the rest of Europe.
But it costs money. That's the point here. The same as assisting the Czechoslovaks, in your example, would have cost money.
The article is trying to make it sound like the money comes back to us, and therefore it's free or something like that. It's not. I'm certainly hoping it's a good long-term geopolitical investment, but it's not free money.
The history of the US defense stockpile post WWII is relevant here .. if new things aren't regularly built the skills pipeline withers, knowledge is lost, old weapons 'rot' as explosives become unstable and the last person that built those particular FPGA target aquisition and guidance cards retires.
For better or worse the US defence industry operates by pushing tanks and shells out of it's back end while building fresh goods to stack on the shelves, all the while employing a good number of US citizens and indirectly pumping money into early tech education.
The question here is if not Ukraine (for the "old stuff") then where?
A much bigger question goes to whether such a bemonth of a weapons R&D | production industry that occupies such a large percentage of the US economy should be scaled back by a factor of five (and still be larger than any other countries).