49 states are at-will employment states. Legally they can be fired for any reason that isn’t a protected class violation.
Typically this is not something that people in the ostensibly pro-worker party celebrate.
One, I’m describing reality not taking a stance. Two, “pro-worker” sometimes means making sure an employee isn’t making his co-workers uncomfortable.
This is not for the employer to decide.
That said...
It's just the mask being pulled back. The left hasn't been "pro-worker" for quite a while.
If by the left you mean the Democratic Party, it is the less anti-worker of the two parties and its current political movements are hardly "going mask off." In recent history, it probably moved the most against workers under the Clinton administration.