If you accept that there weren’t any complaints – and you explicitly do – what is there to excuse?
This is the same defense used by people who act completely surprised when yet another courtroom is found to have exclusive Christian symbolism in it. Oh, no one complained so far, so why would you expect anyone to have done anything about it?!
It’s bullshit for the same reason: The fact that such depictions express the attitude that some people are deserving of unequal treatment by the institution.
No complaint is needed for the institution’s management to know that this depiction expresses that attitude to anyone who comes in. They are responsible for getting rid of it, even if no-one complains.
Are the management supposed to be fucking clairvoyant or something?
They’re supposed to treat everyone equally no matter their religion, sex, ethnicity, etc. That extends to expressing that, and removing expressions that say otherwise.
This is true whether we’re talking about an expression like a Ten Commandments monument which expresses that Abrahamic-religion-followers will be treated specially well, or a huge mural expressing that women are sex objects.
We don’t need anyone to complain about the expression for the management to know this. They should show they’re part of a progressive society and remove these harmful displays before any complaint.