“the airforce guys were very clever and figured out they were buying some fairly powerful computer chips for less than it cost to make them ....”
Actually, a more likely scenario is that they worked out a deal with Sony to unlock the PS3 so that it becomes a more general purpose computer instead of a game machine.
Removing the chips in a PS3 is no easy task. It’s not like the old days where the chips were mounted on the PCB with thru-hole components or surface mount pins. The Cell has hundreds of little solder balls for “pins”. You can remove this kind of chip packaging from a board, but it is very labor intensive and not very reliable.
You also need detailed information on the processor to program the system. Assuming the system hasn’t been hacked, you really can’t do much with the PS3 in Linux mode since there is a lot of restriction as to the hardware you can use on the PS3.
While you are correct that working on BGA components is not for the average Joe, we are talking about the military here. They have plenty of skilled personnel and equipment at hand to efficiently mount and unmount such area array package devices with almost zero difficulty or defects.
The main thing that puts working on these components out of reach of the average tech is that the hand assembly normally requires an x-ray to confirm all connections are on pad and properly flowed.