I think that the only reason Uncle Bud came and talked to them is because he doesn't want them to screw up his "plan", because that's exactly what he said to them.

I also think that he is being nice to them because he wants them to feel like he is their hero and that they're going to be saved by the new heroic Bud. And also because he doesn't want anyone else to have a chance to swoop in and save the day. Another time he did that was when he told Jack he was the only one who could disable the machine.