It works for Oracle (it is famously illegal to publish benchmarks of DB2 vs other engines), I'm sure intel can make it work for them thanks to Oracle's court case(s).
Anyhow, specifics aside, you do make a good point.
* cease and desist orders. They could probably argue improper use of trademark or something. And by "could" I don't mean "they have a legitimate legal case" but rather "a flimsy one but one that is still scary enough that few people might want to take the risk / expense testing the argument in court.
* many benchmarks are ran by reviewers who might have access components before they hit the shelves. It would be trivial for Intel to end that relationship. If it's suppliers further down the chain who are providing samples to journalists and reviewers then Intel might put pressure on those suppliers to end their relationships with said journalists. This might break a few anti-competition laws in the EU but it's not like that's ever stopped businesses in the past.
On a tangential rant: I think the real issue isn't so much whether it is enforceable but rather the simple fact that companies are even allowed to muddy the waters about what basic journalistic and/or consumer rights we have. I'm getting rather fed up of some multi-nationals behaving like they're above the law.
It actually makes it easier for Intel to argue that chips are such specialized bits of equipment that even though your average joe can _get_ one, they won't understand how it works and so only highly trainer professionals who have been certified by Intel would be able to reliably benchmarks their products. "As the average user would interpret the results incorrectly, their publication would hurt intel's bottom line". And suddenly you're 95% of the way to having won the case already.
Isn't that a blessing?