Roderick gave a significant amount of money to the abolitionist cause.
The film is set in the early 19th century. One of Roderick's ancestors was a slave trader, and Roderick is horrified and ashamed about this; in modern times being ashamed of such ancestry is an obvious position, but at the time it would have been a political stance, as while slavery had already been abolished in Massachusetts, the same could not be said for many other states, and abolition was very much an ongoing struggle. In the original story it is also established that Roderick has given quite a bit of his money to charity.Also it just adds to the tragedy of his Sanity Slippage and death if he'd previously been the kind of good person to do something like that. And giving away a lot of money can also be a warning sign for someone being suicidal or expecting to die soon...
