Of course I read the article.
How do they know a machine possibly millions of years more advanced would be limited by physical matter (atoms)?
Just like if you asked an engineer in 1900 if you can reach London in 3 hours, he would assume you must travel on the water and laugh at you. He could not fathom a flying machine that could take you to London during dinner.
People in 1900 could not imagine manmade objects could achieve orbit like the moon and stars. Or that someone could walk on the moon.
Space flight was achieved ~60 years ago and true powered machines of any kind only came to be ~250 years ago (steam powered pumps). Now imagine a race that had 1 million years to tinker with machines! We simply can’t...
You hit one of the reasons the announcement is logical bunk. They are making assumptions on the likelihood of external manipulations of the universe based on internal rules of the universe. It’s like me saying hammers longer than 16 inches can’t exist, because otherwise they would not fit in my toolbox.