“So, a lot of people tested for antibodies with a non-validated test came up positive. It looks to me like they’re detecting people who have had ordinary coronavirus infections—in other words, it’s detecting people who had colds.”
So you know more about the scientists’ study (see link below) than they do, and they’re wrong and you’re right. Sure.
https://www.medrxiv.org/content/10.1101/2020.04.14.20062463v1.full.pdf
I've run hundreds (thousands?) of various immunoassays, and am very familiar with the cross-reactivity problems that almost all antibodies have.
How many immunoassays have you run?