This seems to me like a matter of fundamental religious freedom. I know almost nothing of the back story except what's in the statement. But there must be a back story there somewhere, because it's a criminal charge.
In catch-up mode, I see five LCMS signatories, including two in positions I missed - Tim Quill (whom I remember as being very ill at one time in the not-too-distant past, so prayers availed!) who is General Secretary of the ILC, and Jonathan Shaw, who's now the Director of Church Relations (which I believe was the Al Collver post). Anyway, is there more to the story, given the lack of signature by some of the ILC?
Dave Benke