Scrooge Is Still A Bad Guy
This defense, I think, misses the point by focusing too much on Scrooge's personal habits. As a miser, Scrooge spent little money on himself as well as little money on others. The main moral focus of criticism of Scrooge is his miserliness toward others, particularly the Cratchit family. He not only paid Bob Cratchit too little and made him work in poor conditions, but he was also nasty for the sake of nastiness, snapping at people and going out of his way to disparage their holiday spirit.
Yet there is no necessary connection between Scrooge's personal frugality and his meanness toward others. He could easily continue living in a cold, dark house, eating nothing but gruel, while paying Bob Cratchit a living wage and being pleasant to him.