Exempt employees at G12 and higher is where the company offer a "buyout" for the home at current market price. That is the "big thing" of the relocation. At lower grades is still possible but has to be vouched by management.
As someone suggested, this is the cheapest way for G.M. to let go people without having to pay a single layoff package, which is up to 6 months for exempt employees, 3 for non exempt and a kick in the butt for hourly. In a way, it's a brilliant move, and the company surely love it.
It's up to the people in Ponca to guess how much the closure of the plant will affect the overall economy of the town and guess how much they might lose in their property value in the future.
I think that for most people, a refresh to the resume, and apply to any other viable alternative is going to be a better option in the medium and long term. I don't see how to be loyal to a company who shuts down a plant when others started hiring again.