It's a group that exists to make sure that the standard works for all the members, including media companies that think they can control the flow of information. They don't need to promote HDMI adoption since their members already control pretty much all the TV production.

It's still not clear why the standard wouldn't work by AMD having an open source implementation. I try to give the benefit of the doubt, but in this case, it's hard not to agree with the parent comment: whoever came up with this rule and the people who agreed with it are morons.