[pmiller2]

It's "mandatory" if they want to keep their jobs, but they can "freely" choose to quit. Or, so the party line goes. It's also "mandatory" that you drive on the correct side of the road, but you can "freely" choose not to, and risk arrest, injury, or death.

[psychiatrist24]

But do they officially make the claim that they would fire anybody who doesn't attend?

I personally would want to fire anybody who wants to form a union, if I was in the situation. Why should anybody be forced to employ somebody who wants to make trouble in their organization?

[pmiller2]

Yes. They officially used the word "mandatory."