Capital offense?
I say yes.
I say no. EVEN taking Corn's article as gospel, the evidence does not fit the crime.
Stone was not bringing any new evidence to the conversation. He was merely accepting the debunked story of Guccifer 2.0 at face value - ...that there was nothing to the Russian story. It also matched statements from the Kremlin insisting it had nothing to do with the hack-and-dump attack against Clinton and the Democrats. Stone was echoing and amplifying the disinformation spread by a foreign adversary to hide its information warfare attack against the United States.
There nothing in the article to suggest that Stone believed that the Wiki material was Russian "disinformation", to the contrary he accepted the view of those who asserted that there was little real evidence that Guccifer 2.0 was Russian, let along acting on behalf of the Russian government. He may have wrongly believed it, and thought the anti-Clinton/DNC material authentic but that is not a crime - no more than it is a crime for Steele and Clinton's people believing their material was authentic.
Stone went further than spouting Moscow’s line: He collaborated with the Russians. On Twitter, he hailed Guccifer 2.0 as a “HERO.” (He also called WikiLeaks founder Julian Assange a “hero.”) And in mid-August, in a private Twitter message, Stone asked Guccifer 2.0 to promote a column he had written. Guccifer 2.0 replied: “i’m pleased to say that u r great man. Please tell me if I can help u anyhow. It would be a great pleasure to me.”
In the time since then, the US intelligence community and Mueller have definitively pegged Guccifer 2.0 as a Russian front. That means Stone was promoting and privately communicating with Putin’s operators as they mounted their clandestine operation against the United States. He was doing what he could to legitimize Guccifer 2.0 and spare Russia blame for its cyberwarfare aimed to hurt Clinton and boost Trump. Consequently, Stone was aiding and abetting Putin’s plot against America.
The evidence of substantive and/or knowing nefarious collaboration for any such purpose is negligible. In fact, all the article is actually says is that Stone wanted some promoting of an article he wrote, and Guccifer 2.0 offered to assist in any manner should Stone need it.
So all Stone is guilty of is in trusting that Guccifer 2.0 was not a Russian or worse, a Putin agent, and that the information Guccifer 2.0 had already given the press was accurate. As to a feeler about promoting his book, like most of Mueller's "thriller", the indictment fails to mention if in fact anything came of it.
I am not defending Stone's gullibility, Russian sympathy, or hunger for dirt. Nor would I defend the activity of the Washington Post, New York Times, and every other newspaper and book publisher who has use stolen American classified and top secret data (for more dangerous than DNC political musings) to undermine security operations against our avowed and declared enemies (terrorists, communist state actors, terrorist supporting nations).
And of course I wouldn't defend the decades of cold war liberal and left-wing persons and organizations that worked in secret and collaborating as fellow-travelers and shills of Lenin, Stalin, and various other communist rulers - they knowingly collaborating and promoting the interests of Russia against American security in editorials, union organizing, front groups, innocence clubs, and the like.
But if all that did not rise to the level of "treason", then it is ludicrous to claim today's misplaced sympatric leanings for Russia is treason.