Could someone kindly explain what the advantage is, from the employer's perspective, of locking out workers who have given notice of an imminent strike? Or, from the union's perspective, why this is a problem and worth complaining about? I understand that in general, a lockout is a way to put pressure on the labour force by denying them the opportunity to earn, but in such a case, the workers already announced their intention to forgo that opportunity.
For example, here's an airline doing this: https://www.westjet.com/en-ca/news/2023/the-westjet-group-issues-lockout-notice-in-response-to-alpa-s-st
And here's a port authority doing it (and then rescinding the lockout when the strike was disallowed by the regulator) :
https://www.portvancouver.com/about-us/information-updates/port-of-vancouver-operations-update-58/