I do quibble with the interpretation of the 14th amendment you gave in another post, in which you failed to make a distinction between the original intent of A14 and SCOTUS' Doctrine of Incorporation
That aside, I do agree, indeed I think it undeniable that he is proscribed from infringing on the rights of others.
However, I adamantly deny that his actions infringe on anyone's rights.
Some have argued that this monument just sits there so it does not violate anyones rights. Do you agree that it would be possible for him to infringe on others rights by his choice of adornments for the courthouse?
For instance, would a blink neon sign over the front door saying "JESUS SAVES" be going too far? An altar to Mary in the Rotunda, complete with candles? I think is is quite possible that by his choice of decorations a building manager could seek to inapropriately impose his religious beliefs on the public who is required to use that building.
Whether this particular monument, which Moore has declared has a religious purpose, meets that threshold is a matter of degree. If he had been describing it all along as a purely historical display, it might be possible to leave it there. But he has gone out of his way to state that it is there to make a religous statement.