Earlier quoted context omitted.
Well, the reason for this particular firing is because the risks of keeping this person employed were higher than keeping them employed. One mitigate their risk of getting fired by not being actively detrimental to their employer and even trying to contribute in a meaningful way. Being utterly replaceable is going to get you replaced. Conversely, if you're employable, a company is always at risk of you leaving. It's…
Employability isn't the only factor, there's insurance, health, debt, rising cost of living, visa status, and so on that can make it such that, while you can _technically_ leave at any time, it may be disastrous to do so. Which has knock-on effects like "people with disabilities are pressured to not speak out on social media for fear of losing the job that is covering life-saving treatments" without better protection…
As for "speaking out" on social media, that's not really a loss, it's useless. Talk to a lawyer, if you have a case, they'll take it for free. It's funny that slacktivism is so normalized that people think it's the right thing to do when they are trying to help themselves.