Where is your b-i-l, an Air Force retired colonel, prohibited from entering a military base?
There are some areas of all bases (flight line or command post for example) that would not be generally open to retirees and there may be one or two complete bases that are closed (Sandia and Area 51 for example). I'm retired and I've been on a host of installations from all three services. I drive up, present my ID and am passed right through.
All that is too say that Jesse Ventura is a bumpkin. He may have been a Navy SEAL but he was discharged, not retired. He probably presented himself as from the media and the gate guards said, "No. Thank you." The people, active duty and retired and dependents, who do have business on bases are free to come and go. He didn't have any business and he didn't have any credentials.