mdd:
I was clear that I’m not talking about Paskenning. I was talking about the easy, off-the-bat dismissal of his words, by simply calling it Shver, without even asking a Kasha. Sort of the way you would wave off a Svara from a friend.
Divrei Chulin Shel Talmid Chacham Tzrichin Talmud. How much more so, his Torah, especially what he commited to writing. When something is Shver the first response is Iyun. If that doesn’t help, be Me’ayen more. It’s true that a Posek won’t Pasken like a Daas Yachid, especially when he can’t see the logic. But that is after a real Iyun. Either way, the actual Shita is never dismissed. We do acknowledge that Kitnam Ava Mimasneinu.
Now to your Kasha about reverence. Realize that real, original Ovdei Avoda Zara didn’t believe that their particular Getchka created the world. They only believed that it is one of many in the jungle of gods and goddesses that were worth worshiping. In that light, ancestor worship and saint worship take on more meaning. The Ran is saying that bowing to them as if they were in front of them fits the bill. It is the worship of that other-than-human being.
You mentioned trinity as a reason why Christianity is Avoda Zara. It would seem, though, that although it is Apikursus and it goes against the Ikkur of Hashem Echad, it is still not worship of someone other than the Creator of the universe, even if the discription of Him is a wrong one. Tosafos in Sanhedrin uses this Svara to explain why one may cause a Christian to swear by G-d, even though they are referring to ‘Davar Acher’.