The only reason I'd disagree with this point would be if the PLC formed part of a network and somebody added a write command from another PLC in which their data was misplaced or accidentally spilled into your register range and toggled your unconditioned "Always_Off" bit.
Hopefully this qualifies for a beer token, though cider is my beverage of choice.
I don't think that's even possible with an AB PLC, except in very specific circumstances.*
The only two ways (that I'm aware of) to write from one AB PLC to another are explicit messages, or produced consumed tags.
Produced/consumed tags would require me to set my tag up as a consumed tag, which is beyond the realm of common sanity. An explicit message can't write to a BOOL tag, so the only way this could happen is if you were using one bit of a DINT tag for your disabling bit. And if you need a whole DINT's worth of disabling bits, I have more questions for you.
Of course, there may be another type of PLC that can do some sort of socket-level messaging to my AB PLC, and theoretically, yes, someone could set up a HMI to write to my BOOL tag. But again, if someone has deep enough access to my PLC code that they can identify specific "always off" bits, and update the HMI to manipulate them, they can do far worse.
Spilling into my register range is also only a problem in the older SLC-style PLC's. All the new tag-based controllers don't have registers for you to accidentally overrun.
TL;DR, I feel like I've got a pretty compelling argument against that one, but there have been no other attempts. So if you make it to Melbourne before someone gets in with a better one, I'll buy you that cider. You've probably got a while to wait
*edit: on reflection, it
is somewhat less unlikely in the older SLC-type PLC's, which in fairness the OP was originally referencing with their screenshot. All the more reason to migrate to the Logix platform