I would say yes. The site says, "If you are familiar with vi, just start the editor and begin to edit!" This, to me, implies that the program is "vi-like" enough that, as a user, I'd expect to find usable information about
bvi by learning more about
That said, perhaps I'm thinking this way because my attitude toward the scope of "vi-knowledge" is apparently more along the lines of "vi is (or at least represents) a user interface that has been adopted for many programs, some of them text editors" than "vi is an old text editor." Carpetsmoker's answer to the "What is considered to be vi" question explicitly stated that only text-editors are on-topic. My impulse is to disagree, but I have no principled reason for doing so; it's just a knee-jerk reaction.