If he retired from the military- then yes. If he's a Veteran, but didn't retire from the military, then the rule states:
Honorably discharged veterans with 100 percent Service-connected disability and involuntarily separated service members under the Transition Assistance Management Program. Personnel separated under the Voluntary Separation Incentive (VSI) and Special Separation Benefit (SSB) programs for two years after separation
Medal of Honor Recipients
In other words- if he is eligible to use MWR services at any base (commissary, etc. ) then he is eligible to use SOG.