Even objects that were close to or even touching the top or bottom edges would not cause a violation unless they also crossed the left or right edge, in which case it would be a left or right edge violation, not top or bottom. It would not be possible to have a top edge or bottom edge window violation unless the images were vertically misaligned (out-of-register in the vertical direction such that one eye-view image was either higher or lower than the other).
This opposition is clearly a terminology problem concerning what means a window violation (WV).
If you consider that the WV is the rivalry caused by a part of the content in front that should be displayed outside of the medium for the other eye (of course you can view this with an other viewpoint), then there cannot be WV on top/bottom.
It looks like it is your definition because of the exception you gave for the tome/bottom edge wrongly aligned that create rivalries.
If you consider that the WV is an opposition between the position in depth of the elements and their masking due to the absence of medium where they should be (again there are other ways to view it), then top/bottom can be called WV as well, except if you consider that top and bottom edges have no intrinsic depth and always float where you want whatever the perceived position of the other edges. The way I perceive it is that if the sides are at a certain depth and the canvas is rectangular, the top and bottom are imagined in the same plan and thus elements in front of it can be considered as being in window violation. My brain tolerates it more than violations with rivalries, but not too much, especially when there are other objects near the display medium (e.g. the desk on top of which is the 3DTV).