> The purpose of test equipment is to diagnose weird situations...Its requirements are to be as robust and transparent as practical
That doesn't set a clear-cut boundary, does it? What seems practical to you might be impractical to the test equipment maker - especially when cost is considered. Should the test equipment be robust enough to handle 1000+ amps? I'd say no, someone else (maybe even you) might say yes.
FWIW because the USB PD device is connecting two separate grounds, this same failure could have happened from a single broken ground wire.