Pro capitalists view unions with skepticism or hostility because challenges the system, pro socialists view as a way to fight the power structures and injustice.
Other people just don't want to be involved in unions because is a sensitive topic and are afraid to lost their jobs.
We can see what kind of union this is by the fact that:
1. They aren't going to try and bargain collectively
2. Their announcement claims Timnit Gebru was fired and that was terrible, instead of the obvious truth that she said made obnoxious requests and said she'd resign unless she got them, then was told "OK, we accept your resignation". They're a brand new organisation and they're already misrepresenting reality.
In other words it's going to be nothing like the IBEW or whatever. It's yet another left-wing campaigning organisation, pretending to be a union to try and make the members un-fireable no matter how nasty they become.
But the left/right pendulum swings both ways. It would also protect people from the next kerfuffle over Cancel Culture.
People should have the right to not be threatened with the removal of their livelihood for arbitrary reasons. I mean, there's nothing unreasonable in that position, and its merits can be examined outside of the left/right lens.