Does nobody do a literature search anymore?
This has been done before at least twice: HAVEGE  is the first I know of and CPU Jitter is more recent . Both of these are significantly more sophisticated and credible than what is presented in this paper. HAVEGE has issues with its expansion phase that outputs 32 bits for every bit collected. However, CPU Jitter appears to do a first class job.
Finally, the collection loop in the paper will be optimized to nothing by any half decent compiler which means no randomness.