Mandating the flu vaccine seems very iffy to me.
They can never really predict which strain is going to prevalent each year - they make a pretty good guess, but it is not 100% accurate.
When it comes to mumps, measles, etc. there is only 1 strain to vaccinate against. The flu is a completely different creature altogether.
Plus, if they are offering "get out of jail free" cards to the vaccine maufacturers - that means they know this is not a great idea.