I don't believe someone should be fired from her job for posting a political opinion on Facebook, no matter how despicable it is, but first, the outraged liberals in this thread need to offer a mea culpa.
You always argued when it was a conservative being fired or canceled that the corporation was merely protecting their business interests, and that justifies it. Presumably, that same argument could be used for any instance like this. That Home Depot has a lot of conservative customers. This could hurt sales if word got out around town that this lady was a clerk, or some other lame rationalization like that. Amirite?
So if you want people to condemn this, and reject this sort of cancel culture, here are the steps:
(1) Acknowledge cancel culture exists.
(2) Acknowledge it's wrong because it's harmful to practical free speech (spare us the weeds about illegality, we all understand this is about consequences, not criminality, those consequences are what is backfiring, here) .
(3) Acknowledge you previously justified it when it was someone you didn't like getting canceled, and made arguments like the one I briefly highlighted above.
(4) Admit that argument was wrong. Concede.
Then we can move forward into a brighter, less spiteful, freer world.