Technically, you are correct - there is a such thing as a legal unpaid internship, according to some interpretations of the law. This would be when the student gets more out of it than the business.
However, most unpaid internships, such as the one WePay discussed in its last post, are clearly illegal.
So, A) you were technically wrong and B) you are still wrong in practice.
As a decision maker, I need information about threats and opportunities. As a tinkerer, I like knowing minutiae. My response both indicated the functional value of unpaid internships as not a legal threat and provided a link to a reasonable discussion of the technicalities.
Your statement "You should read the article you linked" doesn't add to the conversation, except as an attack at me. Even if you did not intend it as such, in this circumstance you are suggesting that I did not do my homework (when in fact I was helping observers of our interchange by providing sources.) While I thank you for leading me down the path of exploring this legal oddity, I'd rather you left out aspersions.