I think it a bit too severe , unless he also had engaged in some type of criminal activity (either prior or since) or they had reason to believe he was a danger to society.
Still a lot unknown about his character but the article never mentioned that he had any kind of previous criminal record.
To me, giving 7 years was -- them sending a message , perhaps even to soothe the mmffking anti-gun liberals.
His age, previous service and apparent good character(as a law abiding citizen having served with honor)should have garnered him more leniency imho.
3 years to be suspended and maybe a 500/1000 dollar fine, seems about right to me..--Tyr
18 U.S. Code § 2381-Treason Whoever, owing allegiance to the United States, levies war against them or adheres to their enemies, giving them aid and comfort within the United States or elsewhere, is guilty of treason and shall suffer death, or shall be imprisoned not less than five years and fined under this title but not less than $10,000; and shall be incapable of holding any office under the United States.