Since others could be influenced by seeing the monument, it is a small p promotion of a sort. That is clearly unrelated to the "establishment" which the federal government is constrained from in A1. Regarding the Constitution of the state of Alabama, see emphasis in the following. I gather that is the particular section which is questioned.
SECTION 3
Religious freedom.
That no religion shall be established by law; that no preference shall be given by law to any religious sect, society, denomination, or mode of worship; that no one shall be compelled by law to attend any place of worship; nor to pay any tithes, taxes, or other rate for building or repairing any place of worship, or for maintaining any minister or ministry; that no religious test shall be required as a qualification to any office or public trust under this state; and that the civil rights, privileges, and capacities of any citizen shall not be in any manner affected by his religious principles.
The nub of the matter is that giving preference should refer only to some substantive treatment, not to self-expression of those comprising government bodies.
Government IS the sum total of those comprising government bodies, in this case, the Chief magistrate's ability to Judge impartially has been brought into question due to his own words and actions.
He has given anyone who will ever set foot in his courtroom who is not a Christian, reason to try and get the case dimissed.
I know that if I were a Muslim standing trial, I would challenge Moore's ability to remain impartial.