Employee refused entry into work, served trespass notice

Video shows how the owner and a board member refuse to let this employee in to work because they are not vaccinated. They gave the employee a trespass notice with no previous notice or issue before they even stepped onto the sidewalk!

Employer and board member refused to answer any questions. States they aren't letting the employee go but also served her a trespass notice.

How can one remain employed yet not allowed on the property?

This is how they treat a long time employee?