This is Total B.S.
"The intercepting pilots reported visually seeing the pilot slumped over to the right,..."
Hypoxia would have caused the windows to "ice over"; hence, the F-16 pilots couldn't have seen anything inside the plane.
Depressurization would have frosted the windows. Hypoxia is the human loss of oxygen. It could have many causes.
There was a recent General Aviation crash because a supplier of oxygen bottles filled some with pressurized atmospheric air instead of pressurized O2.
The pilot suffered hypoxia, passed out and was subsequently killed.
Another case was a faulty O2 line that leaked. The copilot suffered hypoxia and fell into unconsciousness but the pilot survived and landed.
None of these hypoxia cases frost windows.