I think, Apostolic order is one thing, pertaining to degrees of sanctity, but hypostatic union means consubstantiality and so is quite another, and is properly reserved to the Holy Trinity only.
I would like to see if Suarez's "appertaining to the order of the Hypostatic Union" is really the same as St. Joseph -- or Blessed Mary -- being "comprised" into it. The seond quote, from Giovanni di Cartagena supports the sense of degrees of sanctity better than the sense of true hypostatic union.
All you say is valid. I copied uncritically from a _The Glories of St. Joseph_. I'm sure that you will find some contextual explanation therein that will make sense of this provoking statement.
-Theo