I wonder if you're "safe" being directly at the point of the cut. Although nothing feels safe about holding an angle grinder spinning full speed as a highly tensioned cable snaps. Actually curious on what the person used. I wonder if they'd keep from releasing it to keep other people from doing the same. Idk, would be cool to find out.
I wonder how much you have to even cut through before it snaps from the pressure. One last strand, a little cut into that. Idk.
Would be pretty rowdy to witness. That said, I'll stay the fuck away from high tension cables. Even with winch cats you're not fucking with it while it's tensioned and most people are smart enough to stay the fuck away from them while they're hooked up.