The answer to this question can be found in Chapter 14, which is when the structure that Allie is forcing everybody to be involved i building takes shape as a box that is tall and has a metal lid. The reactions of the people of Jeronimo vary. The majority of the residents think that Allie is going slighly mad and is building a silo. When they ask Allie what he will store in it, Allie answers with a kind of riddle, saying it is what he will take out that is most important:
He said he was making a monster. 'I'm Doctor Frankenstein!' he howled through his welder's mask.
The indigenous farmers and settlers come to look at the enormous creation that Allie is making and are awed by its size and mystery. Clearly, the creation of Fat Boy is something that boosts their opinion of Allie in the opinion of the indigenous people that associate it with some kind of magic or mysterious force.