I don't agree with this. While the discernable effects of the duplicated frames may be minimal it is still not what is considered Native from the source. Now, if a set capable of 120Hz could be forced to display at the Native 24, 30, or 60 as the source I would then consider that as not processed.
Does it matter to the naked eye? Not usually.
You do not understand how digital video works.
It is not showing a frame for 1/120th of a second, clearing the screen and then showing the second identical frame for 1/120th of a second and so on.
Basically, with digital it is only refreshing the changes in a scene from the previous frame. So if there is a black screen for 5 minutes the Blu-ray player literally sends the information for the black screen and then nothing else for 5 minutes until the scene changes. If subsequently 1 pixel is illuminated, it is not re-sending the tv an image of a black screen with 1 pixel - it simply tells the TV which pixel it wants and which color to make it. That is the beauty of this technology.
So you assertion is completely false. When a Blu-ray is watched on a 120hz TV, the player isn't sending the tv 120 individual frames per second - it sends the info for the first frame - since there are no changes to the image for frames 2,3,4,5 the image is not refreshed - 6/120th of a second later it sends which pixels need to be modified and the tv refreshes those individual pixels to create the new image that is frame 2. It does this 24 times per second.
Everything you see on a 120Hz TV without MotionFlow is displayed at the native fps. With MotionFlow is another story; and the reason it looks fake (because 80% of what you see is "processed"). It is sending frame changes every 1/120ths of a second vs. 5/120ths (24 times) without MotionFlow.