I admit that I really don't know O'Laughlen that well - I have trouble getting a real feel for him.
In his lecture, John Surratt spoke of the gathering at Gautier's Restaurant. Surratt said:
"Arising at last and bringing his fist upon the table he (Booth) said, "Well, gentlemen, if the worst comes to the worst, I shall know what to do."
Some hard words and even threats then passed between him and some of the party. Four of us then arose, one saying, "If I understand you to intimate anything more than the capture of Mr. Lincoln I for one will bid you goodbye."
I assume Arnold was the one who said this, but IMO, O'Laughlen was one of the other three who arose. IMO, O'Laughlen was a guy who was in on it for a potential kidnapping (John, I know your opinion of the kidnapping), but not as an assassin.
As I said, I really have trouble getting a grasp on O'Laughlen, but I have trouble viewing him as an assassin.
At the conspiracy trial, if I recall correctly, O'Laughlen was found not guilty of lying in wait for Grant.