This is the definition of a pretextual retroactive justification. Do you really believe that Donald Trump was personally aware of Shokin's statements regarding Firtash's expedition at the time of the call? Do you think he could tell you, today, who Firtash or Yanukovych are?
REALLY?
Ukraine is inviting the U.S. to investigate corruption involving U.S. interests in Ukraine. Several people outside the Ukraine government have reportedly made themselves available to John Durham. Shokin isn't likely raising his contentions for the first time with this week's affidavit. The bottom line is that the administration has ample reason to discuss corruption with Ukraine, and discuss Biden specifically, beyond just a personal vendetta against Biden.