Stringer,
He's working in the motorpool. Exactly where and doing what I don't know. When he retired he was an E-8 and spent most of his time in the Army working equipment and vehicles from light to tanks. Knowing him I doubt he'll be doing much paperwork, he's more of a hands on guy.
As to his motivation, I'm sure the bonus and significant salary had a major part in his decision. He's been short in funds most of his life so this is a chance for him to get in position to set up his kids for school and maybe have a better retirement than his Army pension would provide.