Not picking on your post in particular Jane but for the umpteenth time in this thread....
This issue is NOT about freedom of speech as it applies to the first amendment. Employers have the discretion to hire, retain and fire employees for violations of company policies over such issues. As has been pointed out here ad nauseum and to no apparent avail for some of us, the tenets of the first amendment apply only to the government, not the private sector.
As 'Mega said earlier, companies can institute a myriad of requirements for their employees that would not be be applicable to the first amendment as it pertains to their choice to either hire, retain or fire said employees. Irrespective of claims made by certain unnamed posters in this thread to the contrary, it is an extremely common practice for employers to require that employees agree to certain specific conditions in order to retain their jobs.
I don't know what else can be said to those of you who still fail to understand this extremely simplistic concept. :dunno: