[joezydeco]

No USB host stack opens itself up just because the transmission circuits have been destroyed.

This isn't the case of a gate that fails open. This is the case of a gate that gets hit by a rocket launcher, which blows the gate open and destroys the datacenter behind it.

[regularfry]

> No USB host stack opens itself up just because the transmission circuits have been destroyed.

I'm not talking about the host, I'm talking about the gates. I've seen a laptop bricked because it got the wrong voltage on the USB pins (I've still got it; motherboard SMT fuse blew and I've not got round to replacing it). From a fire safety perspective, it makes perfect sense for gates to fail open (or undriven, so you can push them open manually) when their controller dies. If you can get to the USB port, that's a perfectly feasible route in.

[compsciphd]

I think the author's point is that if you have exposed USB ports then there is nothing one can do. i.e. no matter how hardened they are, you can just keep on increasing the voltage (relatively easily vs hardening) and you will kill the PC. so one can just as easily pentest by removing the power from the PC without any fatally destructive behavior.