You are right that the Sony bdps1e does not support 24fps but It must be for other reasons. The PS3 was the first bit of AV kit to have HDMI 1.3, and it is the extra data capacity (bandwidth) that it enjoys over 1.1 allowing transfer of over twice the number of gigabits per second. HDMI supports 24-bit colour whereas HDMI 1.3 can support up to 48-bit. For example, my PS3 and Pioneer 'communicate' at 36-bit colour depth.
To translate the rubbish I have written above, HDMI 1.3 introduces billions of colours, greater shades of grey(between the black and white spectrum) and so, better contrast. It also allows lip sync correction, and on the audio front it enables the transfer of Dolby TrueHD and DTS-HD Master Audio.
The fact that HDMI 1.3 allows for so much more information transfer will, by design, enable 1080p (I can't off the top of my head think of any 1920x1080 res. screens that don't have 1.3) however I am not sure that relates directly to the 24fps argument which I assumed was more to do with Hertz than colours.