The way I see this - yes, you can exclude a group of employees for a variety of reasons (as long as your exclusion does not violate some other law - like age, race, etc.). The problem with this request is that it BY DEFINITION seeks to exclude a group of employees that IT WAS/IS ILLEGAL TO HIRE/EMPLOY.
Want to put into a document an exclusion of people you shouldn't have hired, and then CONFESS that you did so by actually excluding them in practice (thereby admitting that you KNOW they are employed illegally)? Yea. Good luck with that.