Unfortunately, just because something is made out of ceramic and has gold legs does not make it Military Grade. As a matter of fact most Military IC's are plastic. Ever heard of MTP? Mil-Temp PLASTIC?
Have you ever heard of MIL-STD-883B? It's a standard that must be met for a chip to be "Military Grade"
The part needs to be assembled to MIL-STD-883B standard.
The part needs to go through reliability screening of the MIL-STD-883B standard.
They have to be tested to handle extreme temperatures from -55 to 125 degrees C. And where the temperatures are extreme and the humidity is high, chips have to be MTH Mil-Temp Hermetic.
And it goes on and on... There is a process the chips have to go through. They have to be tested and proven to work in extreme conditions. They have many many many requirements to meet. You don't just get to gold plate some pins and assume the Military would use it for chr1st sakes!!