Maybe, but perhaps there are still people in play that can make these decisions. Buying KIRO might indeed be a no-brainer. But all bets are off. Stay-Tuned!
https://en.wikipedia.org/wiki/KOVR
https://www.cnn.com/2013/05/16/us/sumner-redstone-fast-facts/index.html
The Last Time we seen CBS converting a contract CBS affiliate into an O&O was in 2005 when CBS bought KOVR 13 Sacramento from Sinclair and in that process CBS was moving the KMAX (UPN in 2005/ CW affiliate in 2018) to the KOVR offices in Sacramento at the time of purchase . Back then when that was taking place the Redstones were in talks with the National Amusements board to split CBS from Viacom at the time when CBS got KOVR 13 and also during that time CBS was in talks to make the CW and shutting down UPN during this change. I'm saying its possible for CBS to get KIRO but unlikely today given CBS's current management reforms after Moonves, the Viacom talks and attempts to make All-Access compete against Netflix and Hulu are the bigger priorities CBS has to deal with today.