errr...I don't think the Cult of Sondheim has anything to do with it in this instance.
In fact, his name has never even been invoked in this thread.
Even if the show was just crummy overall, in terms of score or book and the whole shebang, it's not appropriate for a member of the Broadway community to state publicly that she was "#horrified" by it, and that acting and musicianship is dead.
Whether it be Wonderland or Into the Woods, it's just a lousy thing to do. The Broadway community is infamously close-knit. James undoubtedly is familiar with people involved with the show and vice-versa, either directly or through people.
"...everyone finally shut up, and the audience could enjoy the beginning of the Anatevka Pogram in peace."