Catch up on what happened earlier.
The old guy spent a couple of drinks worth talking to Spence and he convinced him to go with him the following morning. He had an errand to run in south Albuquerque and promised Spence payment if he went with him. What he didn’t tell Spence was that his two grand kids would be with him.
This is a major change in the Story. With Bee being infected finding the "Cure" is now Spence's primary importance. Grandpa and the kids can come with the group or leave. Grandpa decides it's good to stay with the group for now. Spence figures the kids can help find Loot.