there's always room on my list
for those who think of others first.
Keep up the good work.
Oh, and thanks for
the help in the toy shop.
If HD&L's conversation early in the short is anything to go by, they haven't exactly done a lot of selfless things throughout the year, and their other major selfless act in the episode is mentioned in the last lines. Therefore, the part about them "think[ing] of others first" refers to their putting Scrooge's name on the list. They could've added themselves, but not only decided against it, but also added the name of someone they wanted to get a reward. Santa decided to view this not as a sleazy attempt at deception, but as a well-meaning way to tell him to give Scrooge a second chance. He decides that Scrooge does deserve the gift this time, which makes sense considering his portrayal in the film: He regrets being selfish when he was young. He has evidently spent quite a bit of time and money on making his family's Christmas great. In "Mickey's Dog-Gone Christmas", he even buys a snowplow company to help Mickey Mouse find Pluto and downplays his selfless act by saying it was marked down for Christmas. (It's also likely that his general insistence on earning everything fair and square did him a favour — at the very least it shouldn't harm his chances of getting on the Nice List.)
