if he has a retired ID card, he most certainly can use it. he can even reserve rooms for other family members as well, so long as he is staying at the same time.
If he enlisted or was drafted and did not retire from the military (after 20 yrs of service), he would not be eligible unless he was a POW. There are also a few other categories, like DoD employee.
Also, if he did retire and has a retired ID card and has a spouse (mom) then she can also sign you in without the sponsor. My husband is retired USMC but I also have an ID card and often stay there without him with visiting relatives. Its a great hotel!