Yeah, that's the kind of thing I've seen before, lots of circumstantial evidence that makes the claims sound plausible, but then the trail just seems to stop cold.
That it runs cold lodges it firmly in the "we are pointedly not going to talk about it" space, which for me is where the worry even starts. If my little gray hat wearing mind can come up with plausible ways to exploit something like that...
A) I am not that smart
And
B) Someone in a position to pull something like that off has probably already implemented it.
Intel has to have spent quite a bit of money to add any feature that you see; so why would they do that without a strong market case...?
E.g. I've used Intel Platform Trust Technology (PTT) to implement system security features, and AFAIK that runs on ME.
There's your evidence.