Here is some of the information I found on Robert this could update your source information for Date of Birth and Date of Death
*U.S., Department of Veterans Affairs BIRLS Death File, 1850-2010
Name: Robert Bell
Gender: Male
Birth Date: 5 Jul 1931
Death Date: 2 Feb 1991
Cause of Death: Natural
SSN: 147242876
Branch 1: AF
Enlistment Date 1: 31 Jan 1952
Release Date 1: 23 Apr 1952
*U.S., Social Security Death Index, 1935-2014
Name: Robert T. Bell
SSN: 147-24-2876
Last Residence:
29532 Darlington, Darlington, South Carolina, USA
BORN: 5 Jul 1931
Last Benefit: 29532, Darlington, Darlington, South Carolina, United States of America
Died: 2 Feb 1991
State (Year) SSN issued: New Jersey (Before 1951)
At this point I find no proof online to say that the son ever served.
I'm also hesitant of there being truth unless you have other explicit source that Robert is the Father of Bruce
Texas, Divorce Index, 1968-2011
Name: Bonnie F Bell
Estimated birth year: abt 1932
Age: 46
Spouse's Name: Robert Bell
Spouse's Age: 42
Marriage Date: 22 Jul 1976
Number of Children: 0
Divorce Date: 6 Apr 1978
Divorce Place: Navarro, Texas, USA
Best of luck on your searching