They can't pretend simply because it's "one cpu one vote". Unless they go and buy alot of cpus they won't get but one vote. they can knock themself out on getting more cpus though. But I don't think that would scale very well. which is good. 
now of course, you do run up against the issue of how do you make sure that each cpu is only submitting a single hash. i haven't figured that out yet.
The idea has a lot of merit. But we need to find a way to implement it in such a way that most of honest players comply with it. Because as said by Vjudeu, miners can always create N sub-miners etc. now of course, you do run up against the issue of how do you make sure that each cpu is only submitting a single hash. i haven't figured that out yet. The other idea that I suggested along side with JPoW was to create a Placebo Proof-of-Work (PPoW): a group of miners unknowingly run the real PoW and another group of miners unknowingly run only a placebo PoW, a PoW with no hashing computation at all. And we adjust the seize of each group accordingly to get the desired number of miners to run the hash competition. But the issue again is that miners can still ignore the Placebo PoW and just use the traditional PoW disregarding the rules to win the block reward. So, I need to find a way to stop such behavior which I haven't figured that out yet.