Dear Neville,
My position is that it being permissible for the Chief Rabbi to go, does not mean that we have a halachic precedent. Rav Mirvis is a symbolic Jew besides for being a halachic Jew. And then we disagreed over the symbolism. I’m not sure were we stand. But it’s okay if we disagree. (I don’t decide these kinds of questions for anybody in any capacity.)
What irked me the most here was that this is a real Rav, and it is not within the guidelines of halachah to openly question him like this.
PS The line you quoted, was targeting the poster that a Zionistic rabbi has no benefit of the doubt.
On to Schisms!
If your rabbi was looking at Popa’s thread for inspiration to use in her actual responsa, I may break off to form a new coffee room. But not because your rabbi is from a different camp, or even because she has really detrimental ideas. [Halacha is not a factor in schisms. There is a system how to address lack of conformity.] It will be because she is actively trying to lead to matters that I am definitely not going to participate in. Schism is about the future, not the present. In the present I could always go to your rabbi and be aware of our differences. But down the road… Who knows?