So I actually figured something out today, and think it might be a bug(?). When I selected the "separate Greece from Turkey" as my political choice, nothing actually happened - no notification, etc...and the "Degrade Turkish Air Force" option remained as a choice (but the Navy and Army choices disappeared). A few hours into the game Greece launched a 12 plane strike against me, with fighter support, followed by frequent air patrols.
When I re-started the scenario as a test, I chose the "degrade Turkish Air Force" option, and right away I got a pop up stating 40% of Turkish Air Forces were degraded, and all the other choices disappeared.
I re-started a third time, chose the Greek separation (nothing happened again), and then was able to also select the "degrade Turkish Air Force" as an option as well, which again brought up the notification that 40% of the Turkish Air Force was sitting out the fight.