No, that's not how sources work. You don't get to use your assumption that the article is accurate to assert that it will eventually be proven accurate by other sources. That's circular reasoning.
...and if the article's claims aren't true, there wouldn't be any sources to confirm the claims at all. The evidence we've been presented with so far (no sources) is consistent with both possibilities. When you make a claim as big as SemiAccurate did, it's on you to provide sources to back it up. If you can't present any kind of proof, you don't have a story, you have a rumor.
Devil's Advocate here, so you are assuming there is a perfectly secure software implementation in this world, and only Intel has it for their Management Engine? I get your point, SemiAccurate may or may not have an exploit, but I think it goes without saying there is a security hole somewhere in the ME, it just is not publicly known at this point.
