The article represents a detailed analysis. If we confine our use of the word treason to a legal context, I can’t think of any reason not to accept your argument. Then again, I’m not a lawyer.
However, the legal context is not the only one in which the word treason applies to a person’s actions. As I argued in a recent article, “excessive legalism can get in the way of describing certain actions accurately. Synonyms [for treason] include betrayal and faithlessness, both of which can easily apply whether or not a prosecutor feels confident of being able to clear the high bar we rightly set to convict people of such serious crimes within a court of law.”
In times like these I think moral clarity is more important than legal clarity for those of us trying to stand up for our common democratic values. If/when prosecutors are considering indicting Donald Trump, they should turn to the lawbooks to find the crime that best describes his actions. However, given his ongoing betrayal as indicated by his willful refusal to honor both his oath of office and the truth, the word treason in the broader moral sense applies and should be applied.