Firstly the test is not useless....in that I see features in the Gold shots that I have seen regularly with the Gold line of films over the last 20+ years. Yes, the lighting isn't 100% the same but one can instinctively tell what's happening. And having used colour negative film for around 40 years, I know what Gold, Kodacolor (Color Plus) and Superia tend to look like. The test does a good job of representing that.
Is it a scientifically conducted test which would be published in a journal? No. Is it useful? Yes.
I shot another roll of Colorplus 10 days ago including very long exposures for "light painting". I was surprised the Colorplus shots came out better than a roll of UltraMax that I also shot that weekend....though daylight shots in a small forest were lovely on the Ultramax.