As much as I detest Woodward and Bernstein and what they did, I fail to see how what Felt disclosed was illegal let alone treason.
If he was concerned he should have disclosed his concerns to the proper jurisdictional legal authority, not to a couple of then-unknown media punks. It was most certainly not treason, and it may not have been illegal, but it was clearly unethical.
"...I fail to see how what Felt disclosed was illegal..."
My take on this - Whatever Felt knew, he knew because of his position in the FBI. If there were illegal activities on the part of any Administration people, he had a responsibility to the Justice Department, not to Woodward. His taking whatever he knew to the media was a reprehensible act.
Strictly speaking, Deep Throat wouldn't have committed any crimes, but Felt's information came, quite likely, from FBI files. That would be a no-no. At least it was before 1992.