You're right, they are wrong...
Disclosure: My company sells anti-virus software.
Page 11 of the report says, "The statistics in this report are based on malicious files identified by at least 2 (or more) renowned AV vendors in our Scan Cloud. "
To summarise, if SurfRight finds something it thinks might be malware on your computer, it sends the sample to "the cloud", where they have machines loaded with a bunch of AV software to check it. The sample is then "definitely" malware if two or more scanners think it is.
So, you might think that this makes SurfRight less likely to give false positives than any ordinary scanner, after all, two other scanners have "agreed" it's bad. Wrong, for multiple reasons...
Scanners have many settings, some want to help you keep your organisation clear of unauthorised tools installed by naughty users... of course, the BOFH doesn't use that on his machine, he uses it to make sure the Beancounters haven't been installing Network Analyzers.
Some products detect damaged files, remnants of partial disinfections that are inactive, as malware... some bad testers use those files to test other products, and the developers of those other products get told, "Your lousy software doesn't detect BrokenFile.12345, I'm buying something else", so they add detection to improve their scores.
Some legitimate programs have suspicious features, so several products with heuristic or behavioural modules might report them as suspicious.
Testing anti-virus software is a lot more difficult than throwing a bunch of samples at it and counting the hits.