Best way to avoid this update crap is make a copy of borderlands2.exe as it is now, so in case people forgot to tell steam to not autoupdate, you still have the backup copy of the former patch then.
Mine's set to not auto-update (I double-checked), it didn't care much and still updated. I think you have to revoke Steam's online access for that to work.
can you check properties, details of borderlands2.exe, if its still 4706 then no worries.
Nope, I was messing around with the ini settings and frequently restarting the game, so I immediately noticed when he updated, since he refused to start before having downloaded the update. I checked during and right after the update process, and it was always set to "Don't auto-update". Executable version number says 4707 now.