I wouldn't worry too much. I suspect with the correct sort of fs corruption you could crash most kernels anyway [1]. You would need to get the user to mount the inserted USB but that's probably their intent if they have inserted it. FUSE FTW! [2]
In the article linked: The attack vector was such that the attacker could plug the USB key into an unattended, but locked, machine.. then remove it after a couple of seconds and walk off.
The victim would have no idea that while they were away their machine had been compromised.
That is far more insidious than a user simply having their machine crash after the put a foreign USB stick into it. (And at which point they'd just go straight back to the person who gave it to them and yell at them.)
I see. Yes that is worse. I thought we were talking about handing out Linux install media on USB though, which would imply mounting the FS on the target system, involving a similar amount of risk either way. James