John,
As one estimable diocesan leader to another, my comments on things sartorial could never be taken as mockery, surely, because of the old adage, "imitation is the most sincere form of flattery." Here on ALPB-Bay, maybe we can do some garment-swapping so I can get my hands on that frock coat. I'm thinking you ordered the regular one, though, and not the bishop's one; I only saw you and yours from a bit of a distance so I couldn't be sure. If so, you need to take the upgrade and get me the one you're wearing. We're not allowed to use the term "bishop" anyway in the LCMS so I need the clothes to make the point; there was an overture to the last synod convention to assess a $500 fine for such usage, by which we in the Atlantic Diocese (oops, District) would have brought in thousands and thousands of Tetzelian coin into the coffers, had the overture been passed.
As to syncretism, your error as I see it is in establishing hard and fast "fellowship" rubrics for civic events and then making them divisive of and terminal to eucharistic or church fellowship within your denominational group. As you're aware, this whole dialog is in its third or fourth CTCR rescension. Beneath that, I believe the practical question to you is what what constitutes a conscience-binder of the degree that mandates leaving your denominational fellowship.
I don't believe I've ever met or conversed with you, so your decision to boogie from the LCMS was made absent any contact with me and based on whatever public information and denomational decisions you had. And let's face it, if you're going to boogie, you may as well do so elegantly, and you have accomplished that.
Dave Benke