That's a theory worthy of the Rothchilds and the Billdeburgers. Might be something to it, but it's asserting a great deal of understanding regarding the forces involved and likewise presuming that Abraham Lincoln was not the only manipulator rolling the dice with other people's lives.
It's still attacking their motives, and not addressing the principle that it is hypocritical of the USA to object to the very principle which created it; That people have a right to break away from one political body and form another. It is, in fact, the imposition of a sort of collective slavery on another people to compel them to remain with a system of governance which they no longer want.
It was the southen theory. The supporters of the Slave Power thought it up.
Imagine: The government refusing to issue traitors weapons! Quelle Horror!
I would suggest that Lincoln was not in office when the insurrection started.
Lincoln didn’t manipulate Senator Davis’ speech bidding farewell to the Senate.
Lincoln didn’t manipulate Davis when Davis called for 100,000 men from the states in insurrection to support Davis’ war against the United States.