Opinion vs News. Greenwald is clearly expressing his personal opinion on his personal blog/page/substack.

Newspapers generally mark Opinion columns as Opinion. In the case of the NYT article, it's not marked Opinion, but you could reasonably infer it as opinion because it's written as a dialog between two people. However, it's not explicitly marked as opinion, which it should be in order to make it clear that this is just the reporters' opinions.

The NYT headline may be loaded and headlines fitting Betteridge's law may be facile, but there's nothing inherently "Opinion" about it (though the subheading saying "Our tech columnists discuss..." makes it pretty clear what you're about to read).

Meanwhile Greenwald states his Substack is where he's publishing as an independent journalist, so unless you want to start referring to him as an independent pundit (or entertainer, in the style of Fox News primetime), calls for journalistic integrity should absolutely apply equally there.

Absolutely. But Greenwald is writing as a private individual journalist, clearly his own opinions. There's no journalistic integrity rule that says an opinion column cannot be sensationalist, overblown, or even downright wrong.

Also, accusing a man like Greenwald (who resigned from the media organisation that he founded because he disagreed with the direction it was taking) of poor integrity? That's a bit off-base.