The guy bought gun parts and was building guns and failed to register them. You need to register your firearms in New York within 30 days, where he lived. He made thirteen guns and didn't bother registering them. That seems to be what all those charges pertain to.

So I guess what the judge was saying, as dumb as it sounds, is referring to how the 10th Amendment allows stipulations on other Amendments so the defense's argument of "but the 2nd Amendment lets us own guns" doesn't hold water since he failed the other half and failed to register his weapons since that's what the law is in New York.

This is just based off of the article, I haven't read the court transcript to see if it has further context.

Edit: lol I give a tl;dr of the article so people don't have to read it, and I get downvoted. Are we at the point we gotta act like the wokies and put a fat disclaimer beforehand "what I am about to summarize does not reflect my own values...." if just an article summary gets so many people riled up.