The Transfer Rate Tests in that review were performed on an Optiarc AD-7173A, but the Quality Scans were not.
When the term "unreliable scanner" is used on these forums, people are referring to using the drives to perform Quality Scans, i.e. PIE/PIF or C1/C2.
All drives are equally reliable for performing Transfer Rate Tests, but some drives are more useful than others because they tend to show problems that are not detected by other less picky drives. NEC and Optiarc drives are usful for this purpose because they aren't the best readers, so if you get a perfect TRT in one of those drives, there's a very good chance that the disc is also readable in other drives.
IF OTOH you use a very strong reader such as a LiteOn drive for performing the Transfer Rate Tests, you could easily have a perfectly smooth TRT and the disc could still be unreadable in many other drives.