You have to accept the job to lose it - once you accept, you have agreed to comply. So you make your choice at the door, enter or not >> liberty in action. If you subsequently decide you don't like your choice, you can leave (make another choice) >> liberty in action again.
Employment "at will" gives full power to employers. Sure, there are some special categories, but generally they can ensure they get compliance or just replace employees ... although that's actually not so easy if the employees are unionized but I digress ... I have yet to work in a company where a change in T&Cs was based on the consent of the employees. It was obviously legal, but never consensual, e.g. let's reduce the 401K match or remove it temporarily - something agreed when you joined, but then they decide to change it; or let's not pay the performance bonus to everyone this year .... Naturally I've taken stock of my liberty and made an appropriate choice in each instance. Funnily enough, for both examples, its probable that neither would have been possible in a unionized environment.