@Jim *******
Well, I still think the wording is wrong and thus should be considered a grace period, which is an indication to leave but should (in theory) not have any unintended consequences since it's only issued in specific circumstances.
The main one being when your job ends and for some reason, the termination letter has a date only one or two days (or sometimes even the same day) as you go in for work permit/visa cancelation.
I do think the terminology used should be changed to avoid trouble, such as occurred in yr case.