I agree with comments in the first answer. Tom shows himself to be an impractical romantic with his silly suggestions from romantic books he has read. For example, even though they could easily lift the chain holding Tom off the bedpost, Tom wants to saw the leg off Jim’s bed. He even suggests cutting Jim's leg off. Instead of picks and shovels, Tom insists on digging him out with case knives because he has read about this in books. He also insists that the escape should take 37 years. Tom takes several knives and suggests making a saw out of one of them. When Huck suggests borrowing a saw from the
smokehouse instead, Tom is discouraged and gives up on Huck, afraid he will never be able to teach him anything. This kind of silliness continues as Twain changes the character of Tom Sawyer from a cute, sympathetic character to a thoughtless, selfish child interested only in his own amusement.
Tom desires a romantic complicated rescue like the books he has read over the years. The formula of the romantic and tragic prisoner involves cruel conditions and an overly ornamented escape plan. By burdening Jim with the excess baggage of a complex escape, Tom is turning Jim in to a prop in his own personal play. He is objectifying Jim so his romantic desires can be justified. The author is showing the innate cruelty of this view of life. The abolition movement did work to free slaves. But after the Civil War the same area that gave birth to this movement did not want freed slaves moving to their northern towns. There is an ultimate hypocrisy in this. Remember, Twain wrote this living in Connecticut AFTER the end of the Civil War.
Tom turns into a true villain in the story by cruelly subjecting Jim into these ornate plans for his own selfish ends.