I'm just throwing out an opinion here.
I can't make up for some of the stories here of how people were mistreated on their last day, there's no good reason for that and I'm not naive enough to suggest we don't have people in our management ranks who act like that.
But, my guess is, if the request for vacation weeks through December went all the way to the RM and got rejected there, it's not because someone wanted to be petty. Thank the lawyers. Someone at that level was probably advised that if they allowed this vacation, they *could* be exposing the company to losing that language in the labor contract by setting a precedent.
The RM may have said to him/herself, this is a bad deal, but this is the only option I have....