
It’s not the strength they were worried about, it was the temperature at which it weakend, which shouldn’t have been a problem according the the information provided to the pilot.
I don’t know the material data sheet was wrong or the person selling it to him was wrong or lying. We don’t and won’t know, because they didn’t try to identify it.
I always thought that this was because Polaris wasn’t aligned with the Earth’s axis until fairly recently.