"2. There are many people who, after 20 to 30 years in uniform, can't physically do the work required for a servicemember ... "
This argument is valid to a point, but falls down on several others. First, the argument starts to work only if DoD contractors are included in the total number of employees. While a DoD Civilian may cost less than a Uniformed member, a contractor typically costs less than a DoD Civilian, so to carry the cost argument to its logical conclusion, there would be fewer DoD Civlians as well (replaced by contractors).
Second, in 1966, many of those DoD civilians were Wage Grade. Many of the Wage Grade positions have been eliminated in the DoD, as technology has eliminated things like typing pools, the DoD has contracted out many support services (janitors, etc.), and because today up to 50% of weapons system depot maintenance is outsourced to defense contractors. So many of the Wage Grade employees which were eliminated over the last few decades were replaced by GS employees.
Third, the argument does not take into account technology and modern workplace productivity. While it may be more costly to maintain an F-22 than an F-100, at the same time many other tasks have been streamlined an automated. Troubleshooting is automated, inventory is automated, etc. In the white-collar private sector, modern technology has led to dramatic changes in both the composition, and number of the employees. There should be similar productivity increases in the white-collar DoD civilian world, which should have led to fewer DoD civilian employees.
Finally, the fact the DoD white collar GS work force is managed using an Industrial Age blue collar system of timecards and hours suggests the productivity per employee is going to be less than what one can get in the private sector.
Figuring out the right proportions of uniformed personnel, DoD civilians, and contractors is not easy. All three categories have positives and negatives.
We're in uncharted territory now, fighting a long-term war with an all-volunteer force. As SkyPilot pointed out in post #51, there is overlap in training and experience because about 44 percent of DoD civilians who will be affected by the furlough are veterans. I haven't yet seen a percentage of Army spouses, but I'm betting that a clear majority of DoD civilians are either Army spouses or veterans.
The bottom line is these furloughs are going to hurt lots of people in the military community. DoD civilians are not wasting money but rather saving money — though I am the first one to point out that by its very nature, government is less efficient than private-sector business.