Such was the claim of the officer who was the subject of said court martial, General James Wilkinson.
General Wilkinson's take on the reason for his court martial taken from his Memoirs of my own times, Volume 3, by James Wilkinson, Printed 1816:
"I [General James Wilkinson] had been arrested by President Madison, to gratify the personal policy, and vindictive passions, of his secretary of war, General Armstrong; but when I demanded Generals Scott and Macomb, as material witnesses in the cause, they were refused under pretexts of public duty..." .
A relevant document (from Fold3), "War Department, May 23, 1814," to General Wilkinson from Secretary of War Armstrong:
A list of witnesses from the same file: