> However, an argument could be made that in a free society there's a fundamental right to have a dissenting opinion or voice

Of course, there is a fundamental right to have (and express) a dissenting opinion or voice.

There is also a fundamental right to have (and express) displeasure with an opinion or voice, whether dissenting or not.

And there is no fundamental entitlement to a job whose responsibilities include managing the public image of a corporation, and if you are unable to do that in the real circumstances and public image problems the corporation faces, whether or not your own speech acts are the source of that PR problem, you shouldn't expect to continue to have that job.