Here's why. Because HD play mandates HDCP and that is on the receiving end (the HDTV) there is no support to play HD content without a live HDMIC receiver.
Hope this short version of HDMI HDCP is enough to see why this fails.
I have a TH-L37S10Z (TV) and a DMP-BD77 (Bluray) in my lounge each with their own remote.
If I power on the TV, the Bluray remains asleep and I have to power that on separately. This is ok.
When I set a recording to play from the Bluray to watch in my bedroom and power off the lounge TV, it also powers off the Bluray. This is not ok.
Is there a way to power off the TV and leave the Bluray on?