I would have found this acceptable.
"I cannot in good conscience perform this ceremony, but I have arranged for an official who is qualified and willing to do so to be here at the appointed time" is far more acceptable to me.
However, MRD is correct. This was not a member of the clergy ALSO acting as a justice of the peace, but a lay official charged with upholding secular statutes. It matters.
All in all, even more argument that government should be out of the marriage business entirely.
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