With this I think you miss something important:

" should people be fired from their jobs for their political beliefs? My answer is an emphatic no. The logical follow-up is: should people be fired for publicly expressing their political opinions? Again, no."

If you political beliefs and public expressions of opinion are in conflict with your employer's core values or undermine its profitability then yes you should be fired.

Imagine working for an airline and publicly supported the elimination of air travel.