I suspect you are both correct.
Light first. I have two 10w Daylight 6500K CFL bulbs over my 20g tall [=regular] and the plants do fine. This is my QT for new fish, so it runs permanently but usually without any fish. I fertilize with Flourish Comp once weekly as with all tanks I have. I never have algae issues in this tank, and the plants do as well even without fish contributing organics. Now, growth is a bit slower than in the tanks with fish, but the plants do fairly well all things considered.
CO2. This mainly occurs from organics being broken down; respiration of fish, plants and bacteria produces less CO2 by far. So, without knowing the state of the substrate organics in fish mongers' tanks, and the fish load, plus his maintenance routine...it is difficult to estimate possible CO2 levels.
As for Wisteria, I cannot keep this in any tank; even in my 70g which is only 18 inches high and has two T8 tubes, it failed after several months. Now, I accept that other factors may have played into this, as I have very soft water and was not at that time using Equilibrium to raise the GH which was at less than 1 dGH. This may have been a factor too, as calcium deficiency in particular is not going to result in healthy plants.