The author neglects to mention that the Orthodox Church is composed of many churches, many of which have difficulty cooperating with each other.
Regarding the Ukrainian Orthodox laity (I cannot speak about others) -- most have no clue to what "filoque" refers (by the way, the Ukrainian Catholic Church has dropped it from the Creed, with the permission of Rome) and many know little about doctrinal concerns.  Most of their reluctance has to do with what the Catholic Church stands for in their minds -- and that is material for a book.