1) Your point about an intact military crimp testifying to once-fired status is valid. However, my rule is I don't reload unless I put it on the ground or saw someone else put it there from a factory load. My rule may be a bit overly conservative, but brass isn't expensive enough to take chances that can be avoided.
2) Judging solely by the photos at the front of this thread (admittedly, a bit of speculation), this failure had one of three possible causes:
A) The round discharged before the bolt locked and the case separated at the web because it was obturated at the neck and unsupported at the rear; or
B) The case was manufacturered with a bubble or like defect near the web; or
C) The case had been fired and reloaded enough times to develop a work hardening crack just above the web.
Note that the failure point appears close to the point where a sizing die stops working (because of the depth of the shell holder).
Possible Cause A is immaterial for this discussion.
Possible Cause B is troubling, but in the absence of the ability to UT every case, it isn't something we can detect before reloading. On the other hand, such a case probably won't survive its first firing, so reloading it is a moot point.
Possible Cause C is avoided by my rule.