https://www.nlrb.gov/about-nlrb/rights-we-protect/the-law/em...
I guess the OP means that they should be fired for failing to do their job, ie. "convince" the workers to not unionize.
If someone put those managers in charge of "convincing" workers to not unionize, aren't they responsible as well?
And who gave the order to put someone to "convince" them, haven't they failed too?