As i understand it, tzfas lubavitchers are known to be more extreme. The fact that he never responded to my questions regarding if he believes in the last lubavitcher rebbe as the essence of god wrapped in a body, enabling his followers to pray at his gravesite(thereby answering the question of not davening to intermediaries)….makes one wonder if he not only says yechi, but perhaps says ‘boreinu” as well; maybe he says it under his breath. I’ve known people who try to avoid answering such questions because they are not allowed to betray their faith, much as we would try to skirt around questions about lehavdil mechias amalek…we wouldn’t deny it but we’d try to make it less offensive to a secular or very modern person who asks us. So too, believers in the rebbe-god ideology try to beat around the bush and avoid simply saying that no, a tzadik is not god nor is he god wrapped in a body, and one may not pray to him, and that he does not know your thoughts or hear you except when Hashem wants him ( or anyone else, relatives etc) to.
My rebbe Rav Belsky told me that the OU checks out every chabad shochet to see if they’re rebbe god people; not meshichisten – crazy as that might be, it is not avodah zara and would not disqualify one from shechting.