Folks without virtue accuse people of "virtue signalling" as if virtue were a bad thing. These folks would call MLK a social justice warrior engaged in "virtue signalling".
No idea if this applies to the parent topic, but denying that virtue signalling exists is very strange.
Your parent isn't denying that the term should exist, only saying that the people who most frequently use it are just slinging a pejorative without knowing if the person is offline-virtuous or just online-conspicuous-virtuous.
While that is true, it's still worth pointing out that OP did quit his job, which is more than just virtue signaling.
It turns out that some psychologists have publicly criticized the use of that term as it does belittle people who are actually acting virtuously, in addition to conspicuously posting about it..
[1] https://en.wikipedia.org/wiki/Virtue_signalling#Criticism
mlk existed when civil rights were not trendy as it now is, therefore he was surely glad free speech existed.