Originally Posted by Fracball
An offer was made and you declined. Why is it necessary to give your boss another response? I wouldn't send anymore responses related to this issue. Talk privately to his boss or an HR person if you think the firing threat is legit. It would seem your boss and the company will be toast if you are fired over this. Because you would have gone from promotable to expendable for no (seemingly) justified reason.
Sounds to me like he was already deemed expendable. Take it or get fired is not a promotion anywhere I ever worked.