How about criminal behavior?
See 5 USC 8312
I think he'll be fired. The proper procedures appear to have been followed, the recommendation is to terminate his employment.
I have no knowlegde of how that fits into retirement pay, meaning i don;t know whether or not termination for cause is a necessary prerequisite for stripping or diminishing his benefits. If it doesn't, that's a quirk of federal law. Terminated for cause looks pretty bad on the permanent record, compared with orderly separation.