After all, the only reason Olinsky was behind bars was because Voight was allowing Olinsky to take the fall for the murder of Bingham.
After he got the bad news about his friend, all of his focus shifted to solving the mystery of who had Olinsky killed.
Voight was facing more in “Homecoming” than just his own need to avenge Olinsky.
Voight was on the verge of coming clean to Denny Woods at the end of the previous episode, and he even admitted what had happened off-the-record in the beginning of “Homecoming” before he learned of the stabbing.