In the USA, wording of a degree diploma varies. From web search, I found these examples: (… awarded the degree of: )
+ "Bachelor of Science [not a word about major]" (UC-Berkley),
+ "Bachelor of Science Electrical Engineering [no 'in' here, exactly as show]" (U of Colorado).
+ "Bachelor of Science in Electrical Engineering" (MIT),
So, it would imply to me the gentleman can legally sign with the title "Bachelor of Science in Electrical Engineering" but not the title "Electrical Engineer" even in the State he earned the degree.
This is not odd. Most times I receive letters beginning with "Dear Sir,". Should I found myself in England writing a complain letter to some government department, and I sign it as "Sir Rick Law"; it is likely I will get into some kind of trouble. "Sir" has special/legal meaning in England, just as "Engineer" has special/legal meaning in Oregon.
Also, having the knowledge and/or a degree in a craft does not confer the legal right to practice that craft, nor does it confer rights to a title that is defined by the jurisdiction in question.
+ You can have the MD (medical doctor) degree, but until you are certified and licensed in that State, you cannot practice as doctor in medicine in that State.
+ You can have the law degree, but until you pass the Bar exam, you cannot practice law in that State.
So, for example take 1973/1974 Hillary Clinton in Washington DC. Well, she was not a Clinton yet back in 1973/4, but that is irrelevant to the point here. She has her JD degree from Yale but failed DC bar exam. If she write a letter with legal suggestions, she can sign as "Rodham Clinton, JD" but if she sign as "Rodham Clinton, Attorney at Law", she could be in rather big legal trouble. Bill Clinton on the other hand has the JD and passed the Arkansas bar exam. He could practice law there up until the time of his disbarment - for lying under oath (2000/2001).
So, with this one, I think the government bureaucrats in Oregon are right.
Disclaimer – Law is just my last name and I am not a lawyer. Further, I am not pretending to be an engineer, nor am I presenting this as legal advice. However, I am trying to appear smart, insightful, thoughtful, and all those other good things.