The common law rule for employment is that an at-will employee-- that usually means someone not under a written contract-- can be fired for good reason, bad reason, or no reason at all. The big exceptions to that mostly surround civil rights law such as federal, state, and local laws that prohibit discrimination on the basis of race, religion, etc.
It does not sound to me like there is any unlawful discriminatory basis for this, and one could imagine good reasons why a condo association would want to publish employee photos, such as the need of residents to be able to identify them for possible maintenance reasons. Accordingly I think the employees will probably need to decide whether they want to keep their jobs or not.
Of course there may be laws or ordinances in your jurisdiction that would make a difference. The empoyees can certainly hire a lawyer there and ask.
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