"Further, I'm not sure how a ROM option could have affected the OS once the machine had booted."
If you read the article, it says that Ctrl-Alt-Insert was a diagnostics mode which would have been on ROM and that's where the option not to run autoexec.bat was found.
Thus, a ROM change with that option removed would have been the fix. We don't know the machine had a floppy disk.
Pretty sure F5 was only introduced around MS-DOS 6, so if you were running that on a Zenith 286 you've got some other military technology on the go! Could have just lept forward in time to a point where they had the password though....