Willfully retaining classified documents in an unclassified area and refusing to return them when asked, are all things that endanger everyone living in the US. Leakage of a Top Secret document can cause extreme damage to our national security. That is the definition of a document classified as that level.

If you knowingly put the country in danger by exposing highly classified information to a massive security breach, then you may not call yourself a spy, but you are certainly doing the work of one.

That is why these actions are explicitly detailed in the Espionage Act.

BTW, the article is behind a paywall. You may want to add a link to get around it.

The Espionage Act was passed by Congress in 1917, two months after the US entered World War One. The law broadly criminalises the mishandling of government records “relating to the national defense” of the US. It is not strictly used to punish spies seeking to harm the US and in recent years has more often been used to punish whistle-blowers who expose government secrets to journalists. Mr Trump, whose presidency ended on 20 January 2020, was not allowed to hold or possess classified documents as a private citizen, much less in an unauthorised place, after leaving office. But prosecutors say he held on to hundreds of pages of sensitive information one year later at two of his resorts - even after he was asked repeatedly to hand everything over to the National Archives.

He may not be a “spy” but he’s still sharing / selling government secrets to their enemies

“if”

One good thing that might come out of this is Republicans repealing the Espionage Act. It does much more harm than good and is used to go after journalists and whistleblowers.

Trump being indicted is still extremely funny, though. “I did everything right and they indicted meeeee!”