Great observation. Horowitz conclusion doesn't flow from the facts he listed. Just because it was a team conspiracy to exonerate Hillary and stop Trump, does not mean it was not a decision based on political bias.
Horowitz stated he could not conclude the decision made in the Midyear Team investigation was not based on the decision of one invidivual (or Strzok and Page alone) but a team of people therefore it was not based on political bias. And there were different legal bases for the decisions made.