Repro steps:

1. Open provided projects "BugScene" scene
2. Enter Play mode and click on the "BuggedFeature" button
3. Look at the console and see that the private method still outputs its debug.log function. (This should not happen as the method that has the Debug.log function is private)
4. Click on the canvas component "BuggedFeature" in Hierarchy window
5. In the Inspector windows "On Click" windows click on "BuggedScript.Bug" -> "BuggedScript" and see that you can't select "Bug" because it's private, even though it's currently selected and works

Expected result: For the "BuggedScript.Bug" selection to disappear as it's private
Actual result: After making the function "Bug" in "BuggedScript" private, it's still selected in the "On Click" window

Reproduced with: 2017.1.0b4, 5.6.0p4, 5.5.3p2, 5.4.5p1

Note:
Added a video of repro